Ponzi was a Bostonian fraudster who in 1920 guaranteed 50% profits in 45 days.  Lots of people deposited money with him and after early success progressively more and more people got sucked in.  Of course all he was doing was returning the deposits of the many later arrivals as the successful and complete redemptions of the fewer earlier investors - a simple confidence trick.  Eventually the penny dropped - and all the later investors lost all their money.  Amazingly his system still gets used - as it did in 1997 in Albania with the usual results.  Welfare systems for the ageing populations of the western world are financed by the same basic mechanism.