^^ Not all of them, some actually do invest your money, but none-the-less, a ponzi scheme (for those who don't know) is where people use newly invested money to pay old members. For the record, these "schemes" are usually failures and go down in a few days making people lose money.
So why the hell would someone want to invest in a ponzi scheme, yet they know the risk. These are just plain dumb people or those who listen heavily to those "get-rich-quick-scheme" garbage.
The investors are there, if you can get trust, your always a winner. How do you get someone's trust when their mentality is "this is a ponzi scheme, should I risk it."
So trust me, I got more clues then a detective would have...