Is this approach more profitable for PSG than the offer made by Real Madrid, or is the symbolic meaning of this trio for the history of soccer and PSG itself more important than financial profits for the club?
It seems so. If PSG were willing to sell Kylian Mbappe, they would definitely accept the last offer. It looks like they are intending to make him play for them at least for one more season. They want to watch the Messi - Mbappe - Neymar trio in this season. They didn't even care about a gigantic offer like that. They are a rich club and I guess they thought that they would make up for it.
That's what makes it feel weird. It's as if PSG feels confident that Mbappe will change his decision and is willing to do a contract extension and PSG seemingly not too bothered if they have to lose a great player as Mbappe for free.
If it turns out that Mbappe sticks to his decision (don't want to extend his contract) and he decided to pre-contract with Real Madrid (or another club) in the winter transfer windows (January 2022), then there is a possibility that he will not be able to play a full season at PSG because it could be that PSG will put Mbappe on the bench until his contract expires.
I don't think that PSG would run the risk of putting Kylian Mbappe on the bench. He is one of the most important players for them. He has had an enormous role on their successes so far. And they are already aware that Mbappe will leave the team one way or another. I assume that they will respect his choice when he signs a contract with Real Madrid in January. He should be able to play in the starting eleven at PSG till the end of the season. If they decide to do the opposite, then their job will be harder in the Champions League especially..