mbape's decision to join real Madrid is obviously sponsored by his love for his idol christiano Ronaldo and it shows evidently yesterday when he recreated the same speech Ronaldo gave at his welcome ceremony to real Madrid. It would have been an unwise decision for mbape who is at his prime and is seen currently as the best player in the world to go to the Arab team when he hasn't created enough record for himself. Dude is still young and certainly has a lot of potential and contribution to the world of football and his joining real Madrid will only help solidify and make things easier for him.
To be fair, sometimes it is not about money at all, and sometimes it is only about passion. Mbappe, like him or not, is a player who has passion for Real Madrid and he wants to bring UCL and league titles to them, which is a good thing for the team as well because when you have a player that much attached to the club emotionally, you know that you are getting the most out of a player as well.
This may not be always the case, sometimes it is not that easy to get a player to like a club, sometimes players accept a deal because of money, but then they end up not putting 100% as we have seen with many players. Mbappe won't be like that at Real, he will do his best to get cups there. This is of course not a big deal for Real Madrid because they won so many without him as well, so not like they really need him, but having him compared to not having him is an obvious choice, just because they may not need him, doesn't mean that they are not going to use him or want him.
Mbappe could play striker, he seems like a good player for that position and at the same time we are talking about someone who has scored a lot of goals as well, that means we could probably see him play striker and be the finisher they needed.