Players who have the talent to make it to the NFL will (generally) continue to play the game as long as they can. Making more $$$ in college will not change that one iota.
First, because fame can be addictive. But leave that aside, and we'll focus on $$$.
We know by long experience watching NFL (and NBA) players live out their lives that making millions of dollars a year doesn't satiate a desire for more money. Witness the fact that many pro footballers earning 7-figure salaries for multiple years are broke and working for some real estate agency a few years after they leave the league. Sure, they made a lot. But the lavish lifestyle they got used to had them spending it just as fast as they made it.
Starting this make-a-lot, spend-a-lot llifestyle four years earlier (for the few who get the opportunity) isn't going to change the cycle for the better. May even make it worse, since the lads will begin the transition when they're even less mature.
The NFL has nothing to worry about here.
p.s. Many of the arguments in this thread about multi-millionaire business founders and/or CEOs shelling out NIL $$$ neglect to differentiate between corporate capital and personal wealth. A Jeff Bezos, Phil Knight, or Elon Musk type who wanted to (some of these guys care not a whit about college football, others are just as obsessed with it as you and me) can spend tons of $$$ on NIL without ever touching corporate finances. They have a lot of freedom when using their own money.