To assess whether he is a mercenary, he would have to be at a club where he felt a great attachment earning 10 million and see what he would do if someone offered him 15, for example.
The amounts(with unofficial,if any) that Mbappe and Haaland earn make it difficult to value. It is a contract too good.
For his talent, yes, I think he deserves a top salary, one of the highest, whatever is the league where he will play.
For motivation I think he seems one of the most demanding PSG players, more concerned about a competitive squad.