Who exactly falls for this kind of scam? I mean, "send us X and you'll get 2X in return" isn't too awfully different than those scams years ago for plans for a perpetual motion machine or the secrets to a 300 mpg car engine.
I guess the answer to your question would be "normal every day folks." But, still, how does the thinking that leads them to believe this stuff even actually work? I don't get it.