Penis size is a meme. It also has nothing to do with looks. Tons of twinks in the West have massive dongs, too.
It's the same reason people drop someone after finding out they have political beliefs radically different from their own. They don't want to give money (even a little) to someone who reinforces ideals they disagree with. A large chunk of vtuber fans, especially the old ones, assume these girls are outcasts like them. The girls then intentionally avoid doing anything to give a different impression because they want money.
Some even go as far as to mimic these fans. Look at how many Holos play video games or watch movies and then rage when they see riajuu or normalfags. But then they turn their computer off and go sleep with their loving boyfriend. Don't you find that a little bit unethical?
Rushia is one of the Holos who rages the MOST at loving couples and complains the MOST about being lonely. I don't remember exactly how far she's gone, but she has said multiple times she's going to marry a Fandead. She is the ultimate GFE vtuber. She's not a comedian or a gamer. Her fans watch her because they think she's a femcel and they want to support her. Will they ever fuck her? Well, according to her, there's a chance! But even if there isn't one, that's not the point: they want to support a girl who's lonely like they are. Why the fuck would they want to support a girl who has a boyfriend?
>"you'd give a female musician money"
For her music, because she worked for it, and asks for it. All those guys sending her thousands of dollars in superchats get nothing in return. It's welfare - and she doesn't need it.
But even if you're somehow too stupid to understand that, despite how fucking obvious and simple it is, you should be able to understand this: she's a liar. You can't refute that. She lied. Her entire career is one big con. Who cares why men give her money? The point is she scammed them. If you disagree, well, then nobody must be having a mental breakdown right now, and Rushia won't either, because according to you it doesn't actually matter. She'll just say she has a boyfriend and then continue streaming, right? And she won't lose a penny, because it doesn't matter.
For the record, I don't have an oshi and I would never send a woman money. I just have an IQ higher than my chromosome count.