He has been desperately longing to actually leave paris st German for like two seasons now but the thing is the club has been putting him on hold knowing full his value they have refused to let him go and that's why he is leaving the club this time around without renewing because at Real Madrid he stands a bigger chance of actually winning all those trophies he has desired and one of them is the champions league and with the squad Madrid is currently possessing they will definitely do more with the likes of mbappe at their front like attack.
Yes, he wanted to leave for long but the management keep bringing in more players to keep him in the team, yet his aim of becoming a Champions League winner is yet to be achieved despite playing with Messi, Neymar, and a lot of big players that have the Champions League experience; again, Mbappe is a big player that have a great future in the world of football, he is a potential Ballon Dor winner which I am sure he will soon achieve since he has joined the best club in the world of football.
PSG can now sign more players and stop relying on one player to lead the team.
Mbappe has since set eyes on many things to achieve in his career and one of them I believe is also winning the baloon Dior which I know for a certain that id he stays at PSG he will never get a chance to actually lift that award. As for PSG building a team around mbappe, that has been something that has been limiting the club itself because any week he fails to turn up the whole team gets demoralized and this mentality has made mbappe even shine more than his peers at PSG but at Real Madrid the whole set up I feel would be a lot different.