I had a conversation with an old pro league ESL player who of course did a lot of streaming. He had explained to me that most games are like this actually. What they do nowadays is they join the ESL and a bunch of companies like "some gaming mouse company" sponsors these pro gamers and streamers who participate in the pro leagues. They actually pay these young kids salary when they are sponsored. So when these pro gamers are streaming & winning and getting noticed, so is that gaming mouse company, and so is the game that they are playing. The company that owns the game puts some amount of money down for these competitively sponsored teams to compete for during major tournaments. It often looks like this money being provided for tournament is some large amount of money, but the truth is that amount of money these companies fork over for competitive tournaments is much much less than what they would pay for direct commercialism. So in a nutshell this guy explains to me:
1) They find some kids who are amazing at video games.
2) Sponsor these kids and slap commercials across their foreheads.
3) Pay these kids a shitty low salary with some deal attached that they will stream the game for so many hours a month.
4) Young kid starts streaming and many of them get obsessive with it, which results in these companies having a pro gamer that people actually want to watch, broadcasting ultra cheap commercials for them, all day long.
5) Tournament time comes around - Come to find out, these sponsored pro gamers will win all that prize money and then their sponsored contract pretty much makes them give most of it right back to the companies that fronted it to begin with.
So long story short, games only stay in the ESL pro scene so long as the cheap commercialism through the players is worth the money invested for sales.