I've decided I'm going to deconstruct this as diplomatically as possible.
Most guys who have always been the studs on their high school teams don't want to continue their college careers on the bench. They want to play, prove themselves, and go on to the NFL. Realistic or not, everyone wants a fair shake. And why wouldn't we feel bad for guys who didn't get a shot? Don't we all want them to succeed at Syracuse?
Not good enough isn't always the case. There's fit into system, fit into culture, philosophical differences, etc. And so what if a player isn't as good as he was scouted to be? Doesn't mean he should be dead to us. These guys are human, you know.
As others have said, you have the option of switching careers/companies if you're unhappy. Your options in D1 college athletics are to quit or to change schools with penalty. And working as hard as you can isn't going to always be enough. If you do all you can and your manager doesn't think you're of high quality, wouldn't you look to move on?
Sticking things out is not always the answer. Patience won't make an unwinnable situation somehow better. These guys are investing time and their bodies into a pretty improbable dream and only have a few years to do it. If a player thinks he can get to the NFL at a different school, so be it. If they possess a commodity that is valued elsewhere, why not take advantage of that?
I think you're implying that these guys are just spoiled, entitled millennials, when it's really guys trying to maximize their small, rapidly closing opportunity to play college ball.