The types of people who are willing to engage at the worst level to climb to the top of the capitalist system by exploiting themselves and others are likely to have other negative traits. To see people as resources and things not as human beings, to see them as things to exploit to get something from whether that’s sex in this case or money, power, etc.

Yes many of them could use their fame to get laid with adult women, but there are a lot more children for many of them (that seems to be the main audience of youtube for a lot of these big successful streamers, hence their use of that one face that psychology shows gets more kids to click) and as a bonus for these types who see people as things to use, children, teenagers can be manipulated a lot more easily.

A star-struck teenager is going to be a lot more pliable to doing whatever extreme acts you want, to being available, to lavishing the ground you walk on with praise, to unthinkingly defer to whatever you say in conversations, to being a thing to play with as they please than a mature adult woman who has her own life, some perspective, some maturity, can tell when she’s being manipulated or when a guy is putting in nothing and expecting her to do all the work in a relationship.

These guys are not going for teenage girls because they want a healthy, equal relationship built on love and mutual respect that’s stable. They’re going for them because they want to fuck a thing and for that purpose I suppose to these types of men a teenager is as good as a woman because they get off either way and they probably see both as just a set of holes. So misogyny plays a part as well, further reinforcing that people are objects to use for your own benefit but girls and women are especially objects for the use of men without concern for them.

There is something to be said about the sexualization of children, teenagers, etc to be sure as part of it but even without that these guys would be preying on vulnerable young adult women so it’s not like such societal things conjured up this behavior and creep-ness in them.

And the sexualization isn’t just from the perspective of these creep youtubers, it’s from the perspective of the teenage girls/boys who are told to grow up, that sex is maturity and being mature is good, who are trained to sexualize themselves, to get laid, to experience it now now now. They’re simultaneously told that and shamed, not really told what a healthy sexual relationship or relationship looks like, not given real skills to develop their sexuality and explore it in a healthy way by a puritanical culture that says on the one hand everyone should be having sex as soon as you’re in high school if you want to be cool and on the other that sex is bad, you shouldn’t have it, all we’ll tell you is the diseases and pregnancy you can get from it not how to navigate these natural feelings and drives you’re experiencing except through repression. And they’re told that sex is how you get people to like you, sex is how you get praise, showing your nude body is how you get men to lavish you with good feeling words and affection. Many lack impulse control, and frankly in some cases do send nearly unsolicited nudes or flirting to adults they’re head-over-heels infatuated with and offer themselves up to these adults who have no moral compass that tells them to reject such offers as responsible, normal, moral adults would.