I don't grant your premise. There's busywork in everything, and I never found high school to be worse than anything that has come later in life. We've all got to wait in the same line at the supermarket.
When I read nerd complaints about formal education, I get the feeling that the prevailing sentiment is one of entitlement: "if I have to do anything I don't like to do, then the system is broken." Smart kids seem to have this sense of entitlement worse than many people -- probably because they're so easily bored.
Trouble is, you're always going to have to live and work with people who are slower than you are. You can skip out on high school in an attempt to avoid it, take college classes early, rush into graduate school, whatever. Eventually, however, you run smack into the wall of society, and you've got to work within its framework. The ability to persevere through busywork is an extremely valuable skill in that context.