If any team is looking to get Mbappé right now in the team, I believe it will be a very wise decision to wait right now. There is no need to pay a huge amount of money for him when he is going to be a free agent after this season if I am not wrong. So it is a better decision to wait for him and try to get him on the team with the temptation of huge celery. If they try to pay the fee for him right now, they will basically be broke and might not even afford the salary, he’s going to ask for.
On the other hand, if Mbappé has even a single brain cell left, you should leave PSG. He should think about making a legacy. Money will always be there for a player like him.
That was the most probable thing, the contract was just a little away there was no reason to make a move now and wait at least until it was finished.
As for the club, we can even predict from the start about this, even though previously Mbappe refused a big offer from Madrid but the current conditions make him think and actually regret a little with his agreement. I think in this case, now Madrid will definitely sell expensively even before Mbappe has made it clear again that he wants to go to Madrid. Even though this is only based on the opinion that I see at the moment, I still feel that this speculation will sooner or later actually happen and it is only a matter of time.
On the other hand, I also agree with what you said, because when it comes to money I don't think he will have any difficulties with his current form and with the potential he has at his relatively young age.