1) he lacks the maturity to be humble enough to listen to and trust his new coach because no previous AAU or school coach has ever asked him to make that change, or

2) he doesn't feel like there's a need to change because he's always been the best on his team and he's always been able to out talent whoever he played against regardless of what a coach may or may not have said.

You are right that a kid can control his attitude/effort and can change it. But the vast majority of the time when you're working with top recruits and everybody has told them everything they want to hear for the last several years, that willingness to change is slow to come. Some have it, but many don't. And that's why you recruit to emphasize those who do.