I completely agree on most things in school being useless, especially homework. However, I don't know of a single career path one can take where they never have

I completely agree on most things in school being useless, especially homework. However, I don't know of a single career path one can take where they never have to do boring, monotonous, or simply annoying things to succeed. CEOs have to handle investors and bullshit politics, professional athletes have to practice and work out, and even rich retired people had to do plenty of stupid pointless things to get to that point. Shit, even the Queen of England has to make appearances I'm sure she'd rather skip. Don't frame the homework as something he has to do to learn what he already knows, frame it as a stepping stone. If he doesn't do his homework, he will fail out of school. If he fails out of school, his chances of doing what he loves severely diminish (and having to work at Taco Bell is a lot worse than homework). Doing to homework now is the gateway to never having to do homework again.