Why do you feel like you don't belong anywhere?
The feeling of not belonging anywhere is a vastly universal human experience. Everybody has felt it at least once in their lives, but some people feel it all their lives and more deeply. The stereotype is an overthinking introvert who has niche interests and is pretty shy around other people. But there is a difference between social anxiety and feeling like you don't belong. You can be extroverted to the maximum and still feel alone among people.
We have evolved to live in groups of 20 apes in a small tribe. We didn't evolve to live in cities which contain millions. The feeling of not belonging is the feeling of not having a tribe or community. A sense of camaraderie and family. It's not about how much you have in common with people. In my experience, I have been best friends with people who are vastly different from me, but we have the same values, like loyalty, love and purpose.
You don't feel like you belong because...well, you don't belong among those people. It's no crazy mystery. The more you know yourself, the more you know what people you want to have around. They have to share your values and care about your well-being. That annoying feeling of not belonging anywhere is trying to protect you from depleting your energy somewhere where it's not appreciated. It's up to you if you listen to it or not. And it's up to you if you do something about it...or just complain about how alone you feel.
Find your tribe. Find your people. "It's hard", you say. Well, of course, if it were easy...you wouldn't be reading this post.