You don't have to. Spider-Man just runs around, like, doing whatever a spider can and he didn't go to school for it, but usually mutants end up in school because, like, we're school-aged when we get our powers and stuff.

[Tabby herself did not actually attend superhero school regularly. She's an extremely bad student.]

It's good to, like, learn how to control your powers and stuff in a place where it's not gonna matter if you blow something up, though.