Seems that you don't know Mbappé well enough. He's very good at certain things, the best in the world when he has a tiny bit of space. But there's also a lot of things he can't do and I highly doubt he'll be able to improve those to ever reach a goat level. He can't shoot outside the box (his long shots are soft and inaccuracte), can't shoot free kick even if he asked to (this can be improved but he'll never have the nice powershot the best have), can't play as a pivot point when he doesn't face the goal, doesn't work hard defensively (in all fairness this can be improved by a good coach) and never scores more than 1 header a year,. He's limited, he's probably the best limited player in the history of the game. He should consider himself lucky if he ever manages to be better than peak Henry.
The problem is, he wants to be more than that, we've seen him several times trying to do what Neymar does (and fail).