Because they're kids and do not have the experience of an adult professional football player who understands that every person and every position isn't going to be paid the same. Kids don't think like adults, and this is why the NIL/Pay for Play was a bad idea. You've got kids functioning in an adult, professional model, and they simply do not think on that level.
Before the collective bargaining agreement instituted a rookie cap, some of the highest paid NFL players had never played a single down in the NFL. QBs like Sam Bradford and Jamarcus Russell were given tens of millions in guaranteed contracts before they ever threw a pass.
This is happening now with high school kids coming into college football, and I believe this is almost completely unsustainable. How many of us would have been upstanding citizens at age 18, with a million after tax dollars in our pockets and a university full of hot girls?
I don't know if this situation can be fixed because there is no union with whom to have collective bargaining. I'm not offering a solution because I don't know of one. I do however hope that this gets fixed somehow to the benefit of the schools and the players.