Quote from Random.Capital:
"Ponzi-ness" is not a function of who is looking, it's a function of capital structure. There is little doubt many of Madoff's investors knew full well the game was not legit - they just happened to think they were on the right side of the trade.
The OP is right, ever since Reagan increased payroll taxes for the purpose of supporting the Treasuries market, Social Security has become a ponzi. Despite the recent outrage over the proposal that 401k contributions being mandated into Treasury "investments", few commentators seem to have connected the (two) dots and realized that the US has already been doing this with Social Security for 25 years.