I'm not so sure about that. A year or two ago Riot games managed to get one of the LoL pro players an official sportsman recognition, which means extra financial support for their work (granted, I don't know what the details are, but I'm guessing travelling fees and such).
Second, pros tend to stream games on their off hours and people like Maximus Black, who - pro or not - is frankly a joke, yet still rakes in ludicrous ammounts of donations and subscriptions.