All this talk of vtubers "graduating" sounds like a sinister euphemism.
Is idol slang (retiring after getting to old), it was adopted semi ironic by Vtubers and community.
...and paedos. Don't forget the paedos.
As someone that finds vtubers really weird, I've gotta defend Boredfrom. A lot of people like cartoon dogs because they're cute; it doesn't mean they want to bone dogs. A lot of people like cartoon cats because they're cute. It doesn't mean they want to bone cats. And a lot of people like cartoon kids because kids are the very reason our brains evolved the concept of "cute"; it doesn't mean they want to bone kids.
If you're someone that hates kids or are a pedo yourself, I can see why you'd struggle to imagine why people would like them as just being cute. And yeah, a cartoon kid being played by an adult is as weird to me as those Splatoon hologram concerts. But thinking kids are cute is much, much more commonly rooted in human nurturing instinct than in depraved sexual desire. It's why we have a human race.
No denying that the anime demographic does attract more pedos than normal, though. But most probably are not (or at least so I choose to believe), and Boredfrom is probably just a giant, huge mega-nerd with a decent heart (for someone on TheBore).