I think you may even be in the minority. I would expect most fans of twitch streamers to be an actual fan, not there to merely enjoy the game (even tho the game is actually enjoyable to them as well).
On youtube, it is more likely the opposite - "fans" on youtube enjoy the content, more than the youtuber. This is typically why once a youtuber becomes well-known for one type of content, that they cannot switch away (see the countless minecraft content creators that are somewhat burnt out by minecraft, but continues to make it since it is the majority of their views). Content creators who _are_ personalities and can branch out, have already done so to twitch.
I use it like I use sports. Though at first I did learn things, but now it’s solely for watching high end playoff/championship games, sometimes with friends.
I haven’t really donated much outside the thing you get by having an amazon prime subscription. Which is honestly rather silly considering how much money I pay for my NFL subscription.
I think this is an important one. Growing up as kids, we'd often sit next to siblings (or parents) to watch them play games, turning them into a shared experience.
I prefer watching shit on TV with my girlfriend over watching it alone as well; like you said, having someone else react similarly validates your experience.
The first is to check out games I'm interested in. The streamer is mostly incidental unless they're actually getting in the way of seeing the game. YouTube exists for this too, but I find the spaces in between the highlights that you see in streams to be more interesting than the structured reviews.
The second is to watch them play a game I've already played, usually in the hopes they enjoy it too. It's a form of validation of my own experiences, it's just nice to see someone happy at the same things I guess, and also a way to relive a story I might have mostly forgotten but through a fresh perspective.