Ok so coffee is made from coffee beans. And beans are *also* made from beans. Why is nobody making, like, black bean coffee?

Ignoring the fact that coffee beans aren't beans, for the same reason we don't make tea with just any leaf. Someone braver than you tried it and it was disgusting.
- We do make tea with a lot more plants than people realize though.
  
  Absolutely that's why I didn't specify a leaf type. Probably could have said poison ivy and been fine though
  
  No, tea is the name of the plant. If its not made from tea leaves its not bloody tea!!
- Or toxic! Don't forget toxic.
  
  Or even psychedelic. Don't think I need to say not to forget it, because I'm sure you won't be able to 🫠
- Tisane to be pedantic

Coffee isn’t a true bean—it’s more closely related to gardenias.
- Just to piggyback on this. The simple truth is that lot of things are just called things because they resemble other things, either in form or function.
  Coffee is not a bean; beans come from legumes, coffee fruit seeds are roughly bean sized and shaped.
  Cacao and vanilla are also not legumes.
  The peanut is a legume like beans and peas, but the it’s fruit treated like a culinary nut.
  Cashews are not true nuts. They Grow outside the actual fruit.
  Nut milk and butter do not come from mammary glands.
  Tea is made for the leaves of the tea plant (Camellia sinensis), which is a shrub or small tree, but many infusions of dried plant matter are often referred to as teas. The Tea Tree (Melaleuca) of oil fame is a different plant entirely. It got its name because some sailors made a ‘tea’ from its leaves after they ran out of real tea leaves.
  Currants (genus Ribes) are actually named after raisins. Raisins of Corinth were small raisins that were produced and exported from… well… Corinth. Over time ‘Corinth’ morphed into ‘currant’, they dropped the ‘raisins of’, and the local small dryable fruit started being referred to as a currants too. Eventually, production of the tiny raisins migrated to other parts of Greece and some smart guy thought “Hey! Let’s market these fancy tiny raisins that we are importing from Zante (the greek island Zakynthos) by calling them Zante Currants to distinguish them from the common local currants.
  
  And many "flowers" are not flowers at all. Poinsettia is the first one that comes to mind, but there are lots of them.
  
  Thank you for adding this. Lots of fascinating info. TIL!
- Interesting, but the all-knowing Wikipedia seems to agree with you:
  From https://en.wikipedia.org/wiki/Coffee_bean:
  Even though the coffee beans are not technically beans, they are referred to as such because of their resemblance to true beans.
  I'm still tempted to try this, though.
  
  Do not do this with dried beans. Most dried beans are toxic and need to be soaked and boiled for about half an hour to become edible.
  From the Wikipedia page for kidney beans:
  As few as five raw beans or a single undercooked kidney bean can cause severe nausea, diarrhea, vomiting, and abdominal pains.

Instructions unclear, made chili

A lot of things in botany have similar names, but are totally different things. A "strawberry" is a berry only by names (it's closest relative is the hazelnut, IIRC), a "peanut" is no nut, either.
So it should not surprize when one learns that the Cofea plant is a Rubiaceae family plant, not a Fabaceae/Leguminosae family plant, i.e. what we commonly call "beans" like green beans, peas, or, amazingly, peanuts. It is just called a "coffee bean" because it reminded someone back in time of a bean, shapewise.
- The question still stands... Where is my hot green bean juice?!
  
  Have you tried making it yourself? Try roasting and grinding some dried peas or lentils, and report back how you liked that "bean-coffee". Nobody is going to stop you. Do it FOR SCIENCE!
  
  Everywhere if you're determined.
  
  Sitting on a shelf at the grocery store. Get yourself some dried beans, run them through a coffee grinder, and make your disgusting concoction using your preferred brewing method.
- A "strawberry" is a berry only by names (it's closest relative is the hazelnut, IIRC),
  Close relatives to strawberries are other similar plants like Sibbaldia. More distantly related are roses and lots of other fruits like raspberries, apples, peaches and so on. Hazelnuts are even more distantly related (not super far, but also not super close). You're probably thinking of hazelnuts because the small seeds on strawberries are technically nuts.
  
  I stand corrected. Somewhere in the back of my mind I had the idea stored that it is closer to the hazelnut than e.g. apples and peaches. I'll go and refresh my knowledge at the earliest opportunity.
  Nonetheless, it's not a berry.
  
  Not nuts but very close, they're called "achenes" (ə-ˈkēn). The only Important difference is that nuts have a thick, protective shell but we're being specific here.
- So if it's not a bean, what is it? It's not the fruit, so is it the seed?
  
  It actually is the seed of the coffee plant.
  
  IIRC its more like a pit than a seed, but yeah

A vanilla soy late is actually a 3 bean soup.
- Unfortunately only in culinary terms, as neither vanilla nor coffee beans are true beans
  
  My taste buds disagree that this is "unfortunate".
- The vanilla plant is an orchid and not a bean.

coffee is a seed, not a bean, pulse, or legume.

We do in some cases, you've basically described hot coca for instance. But yeah, you might be onto something, roast up some kidney beans and see what happens.
- Cocoa comes from a seed, not a bean. https://en.m.wikipedia.org/wiki/Cocoa_bean
  
  Beans are a particular type of seed.
  
  Coffee is also a seed, not a bean.
- Wait, are cocoa pods beans? What even is a bean?
  
  Ur a bean
  
  https://en.m.wikipedia.org/wiki/Bean
  Bean is admittedly a bit of a fuzzy term. Coffee beans are not technically beans, and probably wouldn't be very good in your chili.

Coffee "beans" are closer to cherry pits than any real bean.
- What about toe beans?
  
  Their beauty is beyond compare.
  
  They aren't close to cherry pits at all.

I drank it in Taiwan among other very low sugar juices that I prefer over plain water. It's just one of many drinks made from ingredients we never thought of, like mushroom drinks and cereal grain drinks. The bean drink must have been forgettable enough that I can't describe the taste after four years away.

https://www.agv.com.tw/product-category/beverages/
- Just wanted to add that tea with black beans, red beans, roasted barley, roasted rice etc are common in Japan. I assume Taiwan has the same, judging from the drinks posted above (the label even says the Japanese name in roman letters).
  
  Barley tea is delicious.

but we don't know if we don't try
Someone probably already tried. Every time you are asking yourself "am I the first one to think of x?", the answer is usually no.
- Maybe after imperialism / colonialism re: tea and tobacco, folks were less inclined? Or they kept it on the DL.
  
  Less inclined to what, experiment with food? Sounds unlikely to me.

No caffeine yo, that's where it's at for most people. But hey, ain't nobody gonna stop you from trying. Let us know how it goes if you ever do try.

You should know that undercooked beans can be poisonous, and it is best to soak them before cooking.
If you do try this please prepare the beans properly first.
- Tf?

I strongly suspect that many of these things have already, uh, been tried.
As for those that clearly made it through at least one round of testing, a self-styled "Weird Explorer" has a YouTube series called "That's not coffee" where he - and occasionally a friend or two - reviews some of them.
Not sure if there's anyone on there who has tried roasting and grinding other sorts of beans for science though. The closest I can think of is the various creators making tofu alternatives from beans that aren't soy, which kind of turns the whole thing on its head: Could you make a tofu from coffee beans? (I'm guessing not, but that's another for-science idea.)

ITT: Because it would be
and possibly poisonous.

Because we're not criminally insane.
But since we're on this fascinating topic, here's a Youtube video about other things people have tried to substitute for coffee during the American civil war. (Hint: not beans.)
- This is/c/nostupidquestions though
  
  But not /c/nostupidanswers.

Because it would taste disgusting, and it doesn't have caffeine, so there's no motivation to drink it.

We have coffee. We have tea.
I assume humans have run hot water through every conceivable plant grounds to see what it would taste like.
- It would suck if poison ivy tea tasted really good

Edit: I need to see what dried beans I have and maybe go shopping. I will give this a try with a couple different types of beans and report back if I fart or not.
Hope you have some alpha-galactosidase at your disposal.
The simplified explanation: A reason beans give some people gas is due to certain types of sugars and carbohydrates they contain. Those sugars are water soluble. Seems like brewing beans would concentrate those sugars and lead to epic tootage.
Also, one method for reducing how much gas that beans cause is to soak them in lots of water. Basically, soak them for up to 8 hours, drain, rinse, and repeat a couple more times. It works on the same principal, that the soaking process will remove at least some of the problematic, water soluble sugars. Supposedly adding a small amount of baking soda helps, too. I'm less certain about that.
- Also aren't kidney beans highly poisonous when consumed dried?
  
  Yes, many beans are, but kidney beans more than most. They need to be soaked and cooked for a significant amount of time to neutralize the toxins.
- "Epic tootage"
  I think that was a Miles Davis album
- I think Alton discusses this on Good Eats, and a long soak doesn't really make a difference (according to him).
  He did have a solution, I just don't recall. May have been baking soda.
  
  Oh, if Alton said that then it must be true. Who's Alton?

My elderly relative in Germany used to drink Caro? Carro? coffee. https://en.m.wikipedia.org/wiki/Caro_(drink) Barely, Rye, and Chicory. Chicory, if I recall correctly is still in various things, including Fiber Snack Bars. I had to look it up since I didn't know what it was and wanted to know if it was bad for me in some way. Turns out, as usual, I should be more concerned about the copious amounts of sugar.
- You can actually buy chicory coffee. I used it for a while as a coffee replacement.
  
  Yeah. It’s very popular in Poland among old people. It reminds them their childhood

That's kind of what aquafaba is but you don't need to grind or roast them, because most times you want aquafaba to be quite thick. I don't know how often it's used elsewhere but I know it can replace egg whites in coctails that call for egg whites.
- Apparently you can even make meringue with it. Haven't tried that but I often make mayonnaise with aquafaba.

Coffee beans aren't beans. There are some beans that are roasted as a substitute for coffee, like the seeds of the Kentucky coffeetree. In times of shortage, people have tried many things to replace coffee, like dandelion and chicory root. For the most part, the substitutes arent as good as the original, so people don't stick with them. There's a chance someone has tried to roast and brew pinto beans or whatever, but they probably taste bad.

Because of the taste? While it's not common to brew a drink with other beans, we eat them all the time, and it's pretty obvious in doing so that they aren't flavors that lend themselves to a beverage.
Coffee beans are actually the seed of a more traditional "fruit" (ie, sweet and acidic) rather than a legume like other beans (also technically seeds, but vegetal in flavor, with an entirely different taste and texture). You're basically just going to get a weak broth from traditional beans.
Similarly, people have tried steeping every type of leaf, plant, and fruit out there in water, but it's a pretty limited list that remains popularly used for tea, as it's a pretty limited list (relative to the incredible diversity of plant life) that actually tastes good that way.
People use mushrooms, various roots (like chicory), other fruity seeds, and more to create coffee-like drinks, and/so with the number of people and cultures out there with their own tastes and traditions, it's a relatively safe bet that if people aren't drinking it anywhere in the world, it's because they've tried it and it just doesn't taste good.

Coffee comes from cherrys
- Come again?
  
  COFFEE COMES FROM CHERRYS
  
  But it's already popped.
- I guess you mean "berries"
  
  A coffee bean is a seed from the Coffea plant and the source for coffee. It is the pit inside the red or purple fruit. This fruit is often referred to as a coffee cherry, and like the cherry, it is a fruit with a pit.
  https://en.wikipedia.org/wiki/Coffee_bean

Isn't that what black bean soup is?
- But with all the solids strained out

Coffee wouldn't be a very popular drink without the caffeine. Find me some caffeinated black beans and I'll try it your way.

chocolate milk?

Let us know how it goes

Coffee is more red/brown than black.

I visited Panama for an agricultural trip about a decade ago where we focused on coffee agriculture and production. Coincidentally, there are some coffees that blend in beans or peanuts to mellow the flavor. This is usually done for cheaper coffees that use robusto beans instead of arabica. It’s also to relieve some of the acrid taste that can develop during the drying out process if the beans are dried around animal droppings.
If you’re interested in what a mellowed coffee would taste like, I think chock full of nuts is a brand you can try in the states.
Edit: ok so I did some more research and it appears that chock full o nuts likely no longer does this, they just have typical coffee nowadays. I’ll leave it to you other internet sleuths to find a brand that does.

You can get it in a can, just gotta’ pour it off before you toss all the beans. Or get one of those big boba straws… pro tip: buy a few cans, there’s just not enough in one.

You could try drinking the juice out of a can of beans 😹

We milk everything plant
Almond, soy, peanut, grape

Probably because of how much taste coffee can be extracted via brewing vs black bean. Probably gonna takes some time to extract the taste of black bean, by then it's might as well be soup.
Also due to the taste and smell.