1. Choice. No one forced them be athletes, nor forced them to be athletes at one specific school. They are choosing to take that road in order to get what they know is available.
2. Compensation. The cost of schooling, especially some particular schools, such as Stanford, Harvard, Duke, etc. are amazingly high. The degree an athlete gets can be quite compensatory.
3. Real world business. My company makes more money from my creations than I make in compensation -- if it were not so, there would be no business there for me to make any money.
All that said, I do see problems with the current system, but I don't think the solution is to compensate the athlete more. Most of the athletes I knew in college (at BYU even) lived way better than I did. I sacrificed more worldly things than they had to. I'm not saying they don't deserve it, just that their "plight" isn't as big as deal as many make it out to be. The reason this is happening in my view is so that P5 schools can use their money to compete for athletes without as much worry for legality. It also is a foot-in-the-door technique to open the way for more and more.
We live in a world where everyone wants everything right now. IMO, the further that we lean toward that end of spectrum, rather than the "earn it" spectrum, the faster we will slide into a monetary and morality abyss that will be very difficult to get out of.