I am not sure that you statement is accurate, I have been using all these social network and I have never been a victim of any kind of Scam; I think the problem is not that the users do not know how to protect themselves; most of the time is lack of knowledge of what should or not should be done online. in other words the average user juts click any link as long they can get what they want, regardless of the consecuences.
my two cents