As much as you can do and as much as you want to do are the same thing. I find this perspective to be very liberating.
No action can be performed without the motivation to initiate it.
Sometimes this relationship is very direct - I want to play video games, therefore I can play video games.
Sometimes it's a bit more obscured. I don't want to fold my laundry, but I do want to be able to find my clothes in my dresser. My desire to find my clothes is greater than my distaste for laundry, therefore, I can fold my laundry.
The language around saying you can't do something is very self-defeating. If I say I can't take care of myself it implies a certain amount of permanency. If I say I don't want to take care of myself, that's temporary and is open to change when I'm feeling better.
More to the point of this meme, thinking that people can help you more than they want to help you is dangerous thinking. The burden of existence sucks, but our fellow humans don't really owe us anything just for existing. They can't help you if they don't want to help you, just like you can't help yourself if you don't want to help yourself.
There's definitely a distinction. There are plenty of times when someone is capable of helping, but chooses not to. Their choice not to help doesn't make them unable, it makes them unwilling. The two are not the same.
Sorry to hear that, dude. IDK your age, but a lot of times life gets a lot easier when you get a little older. Loneliness is a pandemic in modern society. People feel lonelier than ever before, according to multiple surveys. I did too, after I moved across the country. What really helped was picking up outside hobbies, that eventually led to picking up like-minded acquaintances, and a few friends. The cool thing about meeting people while pursuing hobbies is that they're active people, and it's a lot easier to set up reoccurring plans to hang out.
To your overall point, when I was a kid my Mom would not allow me to say "I can't", it was a forbidden phrase in our household. If I ever said it, she forced me to figure out how I could. I disliked it back then because I was mostly just whinging, but it was a valuable life lesson that has benefitted me a lot, especially in early adulthood when things felt so impossible.
I would just like to add that there have been many, many times in my life when I wanted to help, but I didn't know how, or didn't have the means. And sometimes life just sucks, and there isn't anything that can really help.
I hope that, in those times, the people I loved didn't think I didn't help simply because I didn't want to.