The envelope really does come back. Some cases might involve violations of securities laws. As long as people down the line kept believing, he was able to deliver. Eventually, however, Ponzi's shady past and phony present became clear. Ponzi spent three and a half years in jail, but avoided further imprisonment by characteristically jumping bail.
Speculation is, however, a game to be played only by someone who can afford to lose it.
It's little more predictable than casino gambling or playing the horses. The best place for speculation is as part of a diversified investment portfolio. But there's no place for phony speculation schemes. One dependable red flag is that no legitimate speculative investment will ever promise or even strongly suggest a specific return to you. If you are contacted by mail regarding what seems like a fraudulent scheme, contact your local postmaster or the office of the U.S. Postal Service Inspector General.