What's the simplest thing humans are too dumb to grasp?
You ever see a dog that's got its leash tangled the long way round a table leg, and it just cannot grasp what the problem is or how to fix it? It can see all the components laid out in front of it, but it's never going to make the connection.
Obviously some dog breeds are smarter than others, ditto individual dogs - but you get the concept.
Is there an equivalent for humans? What ridiculously simple concept would have aliens facetentacling as they see us stumble around and utterly fail to reason about it?
Gambling. Everyone knows the house always wins and the exact probability of winning any specific lottery but people can't grasp this. I don't know how people look at these massive luxurious casinos and think they win against this company with an unfathomably profitable business model by taking money from people who think they can win.
I think the logic there is not that they constantly win against the casino, but more that they only need to get lucky once or twice. They just see that some people, sometimes win and there is no reason that they would not be the winners. Not sure I'm being clear about it but I hope you get my point.
I play the lottery a few times a year for the following reasons:
-Permission to dream about what I would buy if I won for a few days
-Justification for bitching about not winning the lottery
Instead of buying a ticket I just search the sidewalk for the winning ticket (that someone else lost) while I'm otherwise doing my normal activities. My odds are winning are nearly the same as someone who buys a ticket, so I can dream just as much - but I can spend the money on something else.
First, someone has to have bought the winning ticket. Then, that same person needs to have lost the winning ticket. Next, that person has to have lost that ticket near where you are. And finally, you have to find that lost ticket.
So while both situations are very very far from certainty, and both are approaching zero, one of the two is much, much closer to zero than the other.