Don't discount the damage done by everyone looking for a way to get rich quick. I think something that has driven social online media (in the broadest sense) to become the cesspool it is now, is that people are building their "brand" to profit in some way or the other. This is not to say that previous online communities were not toxic, far from it (lots of epic usenet flamewars to proof the point), however largely people were not trying to "break the system" to somehow make money from it (similar to how spam has almost broken email).