'For another, your friends are chosen by accidents of age and geography, and not by you.'
this seems patently false to me, you hang out with the people who energize and care about you whether you are 16 or 25...
I mean, yes it's true that high school is boring and has many flaws, but it really doesn't take up that much time, and you can get a lot out of it. Classes can be boring and stifling, but I would argue that going to college without at least calculus isn't the best idea if you plan to have a lot of time to learn all the cool math you want/need.
Also, as some previous posters mentioned, until you're kicking everyone's ass and winning math/programming competitions, I don't think it's fair to say that school is too easy