To me it is humorous when people talk about athlete salaries as if these people are filthy rich and are set for life. They aren't.
For me, I make a decent salary. It's enough to live off of and have a little extra, but I am not rich. For me to retire at 65 and live until I'm 90, I will need several million dollars in my retirement account to maintain my standard of living, assuming that social security and medicare are dead by then, and further assuming that I'm not in a nursing home or requiring full or part time assisted living or medical care of some kind. It will take me working until I'm 65 to earn that much, assuming regular annual raises at a percentage that beats inflation by 1% or more each year. It also requires that my 401k earns 10% each year (which it is currently doing).
If I were to retire earlier than 65, the amount I would need to have in my retirement account goes up substantially. Most athletes retire by the age of 40 or, in the case of linemen, much much earlier. For them to live at my standard of living from age 40 until 90 they'd need over 10 million in a retirement account that continues to earn. Despite the high salaries of the NFL, most professional football players aren't making enough money for long enough to get to this point. The ones that do generally get jobs at ESPN or have enough endorsements to not have to worry as much either after football.
Anyway, the moral of the story is, 100k put in an IRA today will be a significant investment in his (or his mom's) future. He may or may not make millions in the NFL, but if it isn't invested well, or if he spends it all living a high profile lifestyle, he's going to be hurting quicker than you might think.