Entitled high school players become entitled college players and entitled NFL players become ?
A lot of these guys have been coddled and handled with care because they can play football and the skids greased for them to the point they think they're privileged characters and now college HC's have gone so far to make guarantees to recruits which is why we're seeing this transfer issue, which is only going to escalate.
Actually, I am surprised we don't see a lot more of this with more players but it is still a small % of the NFL population. Guy gets it in his head he's special and that's not easy to get out of his head. Add to this that most of these blue chippers are slow to mature because they don't have to make the same sacrifices other college students have to make like working a real job while trying to get their diploma.