It really depends on the league. There are lots of soccer players in America only making 60k or so a year despite playing at the highest level of soccer and being fully professional.
Sorry, would you rather me say “tier”? It occupies the top spot in the league pyramid and is fully professionalized.
That MLS isn’t of the highest quality should be obvious to anyone concerned, especially considering I’ve used it as a low paying contrast to “professional sports teams”.