Selling Vinicius Jr. wouldn't solve the problems, because he's a top-quality player, and Real Madrid would be unlikely to find another player of his caliber. If they wanted to sign him, they'd have to pay a very high transfer fee. Therefore, Xabi Alonso must do his part to the best of his ability and maintain a balance between the players. In this case, the team wins.
Are you always willing to seeing Madrid to always rely upon him and his skill? If he performs well, that's acceptable what if he performs badly like the previous games? Come on man! Madrid needs more than one player to shine again. They're a club, and must be working as a team, not rely upon individual.
They can't have two suns in the same club . That's it.
Vinicius doesn't have to be sold to improve the team. In fact, I think having him on the team would make Real Madrid much stronger. I think player egos are perfectly normal, and it's the coach's job to eliminate egos and build chemistry between players.