>>82186340A significant number of anons are in their 30s and have come to realize that lusting after women about a decade or so younger than you is only the result of finding them physically attractive, whereas the age gap can often lead to the realization that you actually find them kind of annoying; they lack maturity, often have different interests, even a distinct way of speaking. Meanwhile, 30+ women are far more relatable, and on top of that, vtubers have the bonus of ageless perfection that comes with the anime "art style", which broadens the appeal for some.
tl;dr, this meme.