That's a lot of money. I get the main star of the team being paid more, after all, even when the team plays bad, that player still brings people to the stadium. Also that star player usually sells the most shirts. I mean, when you have Messi or Ronaldo on the team, who's buying a shirt from any other random player? Atleast with them you can somewhat get your money back, just from the sales alone, let alone sponsorships, etc.
I think it's a common problem in football, and probably in sports, in general, people getting overpayed for no absolute reason.
Also transfer fees nowadays are absurd. Remember when Ronaldo's transfer from MU to RM was €94m (which granted a ton of trophies), and now you pay €100m+ for some random player who may or may not have a good season and then becomes average.