And that's the problem --if you're going to try to apply the near-mythical free market economy to college sports, it will be a mell of a hess to determine fair market value for each player. Plus what if a player shines on one team and would suck on another? That means the other players on the first team deserve more money.
And on and on.
Most 18-year-old males' bodies are still growing. (Some women, too.) And they sure haven't learned and mastered everything that they need to know to play at a pro level.
They need some form of apprenticeship, whether college or underpaid semi-pro, to develop to a true pro level. The 5 stars would be grossly overpaid until people realized how much more time they needed to cook.
And imagine how corrupt the "market" would get --some players would get way more money than their skills deserved, just because they got hot on the recruiting circuit. And you don't think that there would be a lot of crap going on by their handlers, looking for a percentage?