Do you get those funny black-mailing emails? What are they for?

You know the ones which start off something like : "Hey this is REALLY AMAZING, just try forwarding this ... it DOES ACTUALLY WORK" (and it gives an apparently altruistic and beautiful example of life philosophy or the like) continues: "If you forward this email to at least 10 people then the phone will ring resulting in some fantastic news. BUT IF YOU DON'T FORWARD IT, then you will have bad luck for the rest of your life." These emails are seem so cruel and prey on vulnerable peoples fears and insecurities. The thing I don't 'get' is: what do the people who instigate these black-mailing emails feel they achieve? Or do they actually achieve something somehow? I wondered is it just an ego thing that if the email go's all around the world and comes back to the initiator, does it give them a sort of 'control kick' or something?