Lots of streamers seem to approach video games like they're some kind of full time job. They play games, stream the footage then expect thousands of dollars to start coming in every month. Of course the vast majority of them are going to end up frustrated. These people seem to be doing it solely for the money. I get the impression they wouldn't be playing anything if the potential to monetize their "fun time" didn't exist. I've seen successful youtubers force themselves to play games they don't like because of their fanbase, all while complaining about how the game sucks and sometimes even rage quitting. It's cringeworthy.
Why not play the games for the fun of it? It's easier to stream if one starts with that mindset. It costs nothing to stream gaming sessions, so they lose nothing if if nothing comes of it. Even if there's no audience, there are advantages: the stream can be recorded and archived, giving the streamer video footage of great moments they can look back on. People are gonna play games anyway, they might as well stream it.