I think its not only about money that Neymar thinks about a career that has to reach to the top in a competition like UCL. I wont compare Mbappe with Neymar but its really very different in terms of performance because Neymar after suffering an injury his performance dropped and he could not perform as strong as he used to and maybe if he did not get injured maybe after Mbappe left PSG and moved to Bayern Munich, of course Neymar ready to replace his position and his salary will rise.
this is about loyalty to the team with the goal of achieving that must be obtained.
Im also still unsure whether Mbappe wants to join one of the teams in the Bundesliga because Mbappe himself needs a team that can take him to the UCL final and IMO, not Bayern Munich. but lets see where Mbappe will decide because we here dont know for sure where he will go because there is no confirmation from Mbappe.
I am sure that Mbappe only wants Real Madrid and no other team. Or better yet, it looks like it is going that way, and then suddenly he could use that to get even more money out of PSG as well, we do not know if that will happen or not but it could potentially happen.
Think about it, everyone will think that he is leaving for Madrid, even PSG management does, and they will sit down with him to do the contract renewal as just a formality at that point and then they end up with a result that looks like it is going to actually be a situation where Mbappe just stays there and requires a lot of money again. But, most likely situation will be that he will go to Real Madrid and he is going to end up playing there for a long time.