I'm an adult and I watch people play video games...LoL
My favorite is a streamer named Towelliee on Twitch. I watch almost daily. These streamers make bank though. He brings in close to $10 grand A MONTH just off subscribers to his channel. Then there are the sponsorships on top of that. I also lurk on Sodapoppin but his chat is a cesspool 99% of the time because it's all kids.
If you are a girl and have any interest in games, you don't even have to have video. One Sunday I streamed myself playing World of Warcraft and got a bunch of followers...and I never showed my face, just audio. Oh and I play badly. From some reason guy gamers like backseat gaming when girls are playing.
Honestly I watch because I love the game but never have time to play so I watch people who do and get to see new content.