It will be scary if the clubs from the oil countries start buying up the current top players not to the European clubs they own, but to the clubs of their countries. This is going to be really scary.
I believe that it is not so easy to convince most high level players to play in the Saudi league. The country is very different from the West and the league is not as desirable if the player is thinking about his national team and world cup.
I can understand the salary of Mbappé (but I don't agree) because it's a young player, can really help PSG win titles, sell merchandise all over the world, he's the face of PSG etc.
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For players, all countries are about the same - they mostly live in special conditions. During the season, they need to engage in training and games, and if they really want to, then no one bothers to sit on a private jet and be anywhere in a couple of hours.
Now young talented players choose Europe because the sheikhs pay them space money in Europe. Imagine what would happen if Rashford chose not between United and PSG with a salary of a million a week, but between PSG with a salary of 250 thousand a week and some Arab club with a salary of a million a week. I'm not at all sure that he will choose Europe.