In most sports leagues the vast majority of player income is salary from their team. There is something approaching a power law around endorsement money, even in the NBA it’s really only the top 10 earners who make more than 20-30% on their non-basketball revenue streams.

This is true for soccer, but almost all American athletes make the vast majority of their income off team salary.

Not really. Endorsements and Advertising are a good cut of the money but most of the big money in streaming is coming directly from fans, whether through premium subscriptions or donations.