There have always been creepers, but I think this specific phenomena has been in development since no fault divorce became the law. Women pretty much always get the kids in the divorce and they can't really replace a father for a boy.

Boys are supposed to interact with an older social group of men who teach them what being masculine is all about. With a 50% divorce rate in many decades you suddenly have tons of boys who grow up with no earthly idea what masculinity is about. If they manage to have their own kids they fail to pass down masculinity to their children as well in a vicious cycle.

When they grow up they aren't masculine and quickly figure out that women aren't attracted to them. This is quite puzzling because they have been brainwashed by the media as to what women supposedly want and they are trying to emulate it but it isn't working.

Social rejection is pretty painful and after a long enough time they think that there is something fundamentally wrong with them and it starts to brew the self-hatred. They then direct the self-hatred back outward towards the women that reject them because it's easier to cope with "she's just a dumb bitch" rather than "there's something wrong with me."