Uhh... hehe.
A) MMO's attract anti-social people, since you don't gotta interact with anybody IRL. (Not saying all players are anti-social, just saying it's attractive to people who are like that) Granted, the REALLY seriously affected anti-socials wouldn't even consider a multiplayer game...
B) Scammers are generally anti-social, in that they don't give a shit about other people they don't know. Now, a lot of scammers are very smooth with people in order to get what they want, but that doesn't mean they're not anti-social.
Put these two together, and you have anti-social heaven.