@Shuichi Your story makes me wonder if your friend’s parents buy her stuff in lieu of giving her love. You usually do drugs because you are in pain, and all those other actions (cutting, drugging and stripping) are designed to get attention—the kind that makes you think people like you or value you. That’s usually because you aren’t getting that at home. It is also often a consequence of abuse.
I think a lot of kids grow up faster these days because all kinds of this stuff is happening. People are more alienated and more desperate to find love and approval. That’s why kids act in these ways. Sex, of course, is about closeness and love, even if you have no idea why you are doing it, and even if you think it can be separated from caring relationships.
Of course, using it like that makes the situation worse. You can’t really separate sex and caring, and if you do, you lose a part of yourself that wanted a real relationship. It gets pushed down, and you get cynical about relationships and love, and then it becomes a vicious cycle, separating people further and further from themselves.
I don’t know how prevalent this is. People love to complain about how parents don’t parent any more. The people here all say they are good parents, and I believe them. I don’t know how many tweens are having sex—nor whether that rate is higher than it was before. In the absence of that kind of data, we can’t know if this is something we just happen to see a lot of, or pay attention to more, or if it is something real.