Most VTuber fans are pedophiles/lolicons. This is due to the fact that most VTubers are child-like tranime girls (or straight-up child/loli characters) who at the very least either dress up in childish clothing, have high-pitched baby voices, or (most commonly) both, which is bound to attract porn-addicted lolicons.
A common feature in the psychology of a pedophile is that they are turned on by cute characters.
Some VTubers feel uncomfortable towards this fact, while most (specifically the Judeo-Japanese companies they work for) capitalize off it by making the VTuber's model appear more childlike and even go as far as to sexualize them.