Vinicius has understood very well that if he continues his haughty behavior in the Madrid squad, he will be out of the squad. Madrid has always been a strong as a team. They do not want to be rely on any particular player. So if Vini is arrogant, then its effect will be seen in Madrid's overall gameplay and Madrid's attacking performance will become weak. If this happens, the Madrid management will definitely decide to sell Vini. And that is why now we can see the friendly relationship between Mbappe and Vini.
If Vini was some average player in the team, i bet Real Madrid would have sold him before now. With his attitude as most people complain, what is keeping him in the team is obviously his contribution in matches, knowing how hard it will be to fix his position if he leaves. Vinicius was the key player at Madrid before Mbappe entered, there will always be competition in the squad. Mbappe always do same even when he was at PSG.