You may have heard of Don Lapre (video here), the manic TV spokesperson, promising riches to anyone that would follow his system.
Well, he died/committed suicide in prison, awaiting trial on charges of mail fraud, wire fraud, money laundering and conspiracy.
True, Mr. Lapre had not gone to trial, but authorities felt something was wrong enough to charge him with several serious crimes.
It's a jungle out there, and without knowledge you are toast.
Link to my previous post about American Greed, the most excellent television series about real life financial frauds. There is some wild stuff on that show (you can watch it online).