Definition from http://www.sec.gov/answers/ponzi.htm :
What is a Ponzi scheme?
A Ponzi scheme is an investment fraud that involves the payment of purported returns to existing investors from funds contributed by new investors. Ponzi scheme organizers often solicit new investors by promising to invest funds in opportunities claimed to generate high returns with little or no risk. In many Ponzi schemes, the fraudsters focus on attracting new money to make promised payments to earlier-stage investors and to use for personal expenses, instead of engaging in any legitimate investment activity.
Normal bank lending/borrowing hardly fits this criteria. Nor does the vast majority of housing transactions.
