unless he's drafted in the first 2 rounds, he's not going to have $3 million after 3 years unless he has a great agent and fulfills every incentive on the contract. you clearly don't know what these guys actually make.
and do you think a lot of them would actually make it in college if they didn't have the academic support that the athletes get?
What is the league minimum, like $500k per year? That's still better than 99 percent of people on here are ever going to do, regardless of degree or where they got it.
Also, you're not taking in to consideration that kids can get injured while playing for their schools. That means every snap they play for a university risks their future earnings
rookie minimum is $450k annually, which gets taxed down to about $260k after federal tax, then you have to tack on state tax (unless he plays in tennessee, texas, florida, or washington). then he has to pay his agent 4-10% of his gross salary, so $18-45k. then he has to pay the union $15k every year. you're looking at about $717,000 at the end of 3 years using the lowest end of the agent pay and not counting potential state income tax, and that's completely discounting all of the hangers-on with family and friends, and whatever stupid purchases young athletes tend to make.
as for your second point, unless they go to a ****hole of a university, the school pays for the medical costs and lets them fulfill their degrees if they get hurt.