The consequence for Mbappe if he insists on staying at PSG is that he will not get a prestigious title because of PSG's monotony which is only in and in power in domestic competitions only.
Reflecting on Haaland's case when he was at Dortmund he didn't get many titles both individually and in the club but when he met the right club (Manchester City) he turned into a terrible figure.
At the moment Mbappe can also still, he will not get anything if he continues at PSG (except only money) and maybe it would be much better if he looks for a new challenge by finding a club that suits him.
if this is true what you said can we speculate if Mbappe wants to continue his career to be successful must go through a transfer to Real Madrid to break through to the champions league final? I think this makes sense because if you just want a big salary PSG is the best place for that but if you want a better career maybe the chances of moving to Real Madrid are much better to get a title in the UCL.
but in fact we know that it is not that easy for us to speculate because Mbappe and PSG themselves have to go through this unfinished problem and it is difficult to find information that is really real. on the one hand Mbappe himself is still at PSG until next year and this is to be confused whether his contract will be extended or will only be sold.
I believe he wanted both and he did both. How come? Well he got a ton of money from PSG, which he already got and will get the rest this season as well, this way he has covered the money part of his career, from here on out he could get paid a normal amount of money and that would be fine for him.
Instead of getting like 100+ million signing bonus and 60 million salary, he could accept something like more normal signing bonus, and maybe like 30-40 million a year salary, that way he would be in Real Madrid and get good results as well for his career. This allows him to both have money thanks to his PSG contract that is ending, but also have enough to move to Madrid later on and start having some good career in his future as well.