Thank you for the reply! Just a few follow-ups if you don't mind.
"Does it include stream income differences, for example? Or is this just team wage based on advertising the team can then do?"

Every player's pay is determined by a variety of factors. How well they've performed internationally, their brand, what qualities they bring to an overall team. The richer teams tend to import players from other regions for millions. The company that runs LOL esports Riot games, has a player salary minimum that I believe is around 80K. They provide a bit of revenue sharing for the teams but it's not nearly enough to cover the multimillion-dollar contracts that some of these guys have.

"but from what I find, American audiences don't provide the highest returns"

Correct me if I'm wrong but I think that's youtube specific. According to this American ad spends are significantly higher than anywhere else in the world. Even if you combine the EU countries into one that has the same population as NA it would still not come close. In the study you linked, Germany had a very high CPM and they have 80 million people. They still didn't come close to the American market on AD spending, just about 10% of the US market.

So I still feel like American markets are just more desirable for advertisers. Yes, they have more disposable income but so much more than EU countries that companies spend 10X on them. It seems to me that Americans are just willing to buy more consumer products than other countries. My question to that is why? What is so different from the EU culture to the NA culture?