Erm. Ronaldo? People have different mentalities. If he is that determined to become the best in the world, no amount of self promotion will stop him from doing it.
Some players, ala Depay, do not seem to have this kind of mentality. As for if Pogba can handle it, we shall see. But so far, nothing has pointed to the fact that what he does off the pitch is affecting his development.
Here's the big difference: Ronaldo was already at the top when he went into self-promotion mode. He had nothing to prove at that point. He exploded in 2007, carried through in 2008 and only started his narcissistic media appearances after his Madrid transfer.
George Best was not a top player for long. His lifestyle got the better of him. People forget how fast he went down that spiral after asserting himself as the best.
Messi has nothing to prove to anyone. Besides, he seems to be slightly autistic.
But the thing about all those guys is that they timed it perfectly. They became champions, then they allowed themselves to do whatever they fancied.
It's not the lifestyle as in drinking and partying. He's not a Brazilian, he should be fine. It's how he carries himself. He is very, very, very flashy.