This is just the bad business of having players getting paid in any official above board capacity. It's going to happen.
Let's assume the kid got what he was promised and is bailing because after he won those 3 games other programs came with way more money than he's making this year. I assume he's been paid for this year partially but not entirely.
Yes, it makes him a huge asshole to quit on his team. Yes, it's completely immoral to do it.
But... He's never going to sniff an NFL roster. If I have it correctly this is his final season of college football eligibility if he doesn't redshirt. By bailing now he has the opportunity to add potentially another $750k+ for next year most likely?
If he's smart with his money, lives frugally, and he invests it that's potentially life changing money that he can use to limit the amount of time in his life he has to work a real soul sucking job. Honestly, it sucks but if you have that opportunity it's hard to pass it up.