That's a bigger question, like why do people watch streamers in the first place. It's not for me personally but it's a huge worldwide multibillion industry so plenty of people enjoy it and / or aspire to be it.

I didn't get it when it first was a thing (like 15 years ago) but now I watch streams of esports/pvp and I watch longplays to scratch an itch for games I have no intention of putting the full time sink into but need to experience bits of the game (like FF7Remake). Being able to skip or passively consume the boring bits is good and it's less addictive than playing.

Occasionally if they are genuinely funny or are a personality I care about, I find the streamer can be additive to the experience.

For example it was quite hilarious and interesting seeing Justin Wong of street fighter fame trying out Elden Ring. Same for Demetrious Johnson from UFC

It's not really the same thing.

"Normal" streamers are watched for a variety of reasons: maybe their personality is entertaining and charismatic, maybe they're really good at the game(s) they play (speedrunners in particular fall into this camp), and so on. There will always be viewers watching purely for parasocial reasons, but it's usually not the primary reason to watch them.

With vtubers, though, the parasocial element is essentially the full extent of the appeal. They're not very charismatic (vtuber humor is infamous for consisting mostly of loud childish noises and sex jokes), they're usually not very good at games and rarely dedicate themselves to one game or one genre. They are watched because the viewers are lonely and want to feel like they have a (girl)friend, that's about it.

I can at least understand why someone watches a streamer, even though it isn't for me. Streamers tend to be charismatic and entertaining, so watching the person do his or her thing makes sense. But I can't understand the desire to watch a broadcast of a fake persona.