I had a big debate with my friend and friends dad about this. I agree with you 100%, but they were saying some do not really have a "choice." A lot are born into poverty, didn't finish their degrees, or really didnt earn there degrees. Football is the only way they can help there families get out of the ghetto or make something of themselves. While I don't agree with this completely, just some food for thought.
They were born into poverty but 99.9% were given a free ride to the best universities in the country. The choice to leave early and not finish school is a decision each player has to make. They all have a choice. They might get bad advice or be mislead by relatives crying poor, but they could easily go to school in the summers to finish their degree. 85% of pro athletes are bankrupt 3 years after their careers are over. The average pro career is about 3 years. If a player chooses to run for the money it's free will. If he eds up playing in the league for 20 years and suffers body altering injuries, it's free will.