Especially for the more intellectually challenged players at some of the football factories. The average NFL career is 3.3 years and the median salary is $860,000. That's $2,838,000 in earnings. Also, don't you have to stay in the league 5+ years to qualify for the pension?
A lot of those players aren't qualified to do much after their football careers are over. I know several who are coaching HS football now. Not that there is anything wrong with that.
On the other hand, if you go to ND and take academics seriously (with a good major), you have the opportunity to make a lot of money. Not in 3 years, but your long-term career will be more lucrative than a guy with a head full of rocks who plays 3 or 4 years in the league. Also, I think NFL minimum salaries are around $450k.