That's correct, the valuation on Kylian Mbappe is Insanely crazy, Real Madrid shouldn't make such a useless move for Kylian Mbappe, besides they once did and saw him turning them down. He missed his chance, now everything's difference and difficult to get him.
Good example you gave there, Real Madrid spent too much on Eden Hazard and finally got no service from him. I hope they get to learn from that.
This time, Real Madrid is careful enough to spend a lot of money again, even though it was to bring in Mbappe, one of RealMadrid's dream players and targets for the past few seasons. But unfortunately, Real Madrid has also spent a lot of money to bring in young players before, which incidentally is expensive but still young. And right now, they still need several players for other positions. With such a high price that PSG expects, maybe yes, it's a little difficult to get Mbappe at the moment, unless PSG wants to lower the price again and reach an agreement, than they have to lose Mbappe at future transfer window.