it’s rockstar syndrome, same as always. People who become famous for being good at something start to think of themselves as invincible. Combine that with minors specifically treating the rockstar like they are a god that could do no wrong, and any pedophilic tendencies are gonna worm their way out.
With online celebrities specifically, I think the unique circumstance is that people can go from unknown to world-famous in a relatively short span of time, and they haven’t learned how to conduct themselves in that context in a way that they might if they achieved that fame more slowly. For a recently famous person like that, direct DM access to fans is a dangerous thing.