You're going to have a really hard time convincing me that it is never in a person's best interest to receive more money than they had before. In fact, I'd bet all the money I have that overall, people who receive financial windfalls end up much better off in the long run than people who don't.
You're also going to have a hard time convincing me that this money will send kids into a spiral of sex, drugs, and rock and roll. They are already able to stay on the straight and narrow just to have a chance at playing football for free. Giving them an NIL payment will give them an even bigger incentive to stay clean, show up on time, and perform at a high level.
Yes, there will always be people who are irresponsible with money. But those people will end up broke with or without an NIL deal. They'll just have a lot more fun in-between with the NIL deal. And of course many others will be smarter and realize this is likely a one-time windfall and they'll invest the money wisely. There will be hundreds of different outcomes because there will be hundreds of individuals making their own financial decisions.