Because if you allow them to capitalize on earning potential prior, either through direct university compensation or the ability to profit off their likeness, you reduce the importance of those future cash flows and create a structure by which you can incentivize players to participate in bowl games (additional pay for bowl instead of just free headphones). Right now, if you are an NFL-caliber player, in particular a potential first-round pick, your college years offer significant opportunity for downside with limited chance of upside. Like, imagine what McCaffrey could have done in endorsement money this year. Or what Vince Young could have done in the early 2000s. Or Joey Bosa last year. If the NFL is the only way these players can make money, and if the gulf between what they could potentially earn in college and what they can actually earn once leaving college continues to widen, the only way to resolve that incentive structure is to allow players to get paid, which they should be anyways. Like, imagine if you were a creative writing major or jazz sax player and you were told that any profits from books or CDs had to go back to the school, but you could go for free. That's what we're doing with athletes. Should they all make millions? Nope. But they shouldn't make nothing either, and the skipping bowl games is a symptom of the problem.