after three major financial crises in the past 20 years, it’s hard to call private finance “safe” from ponzi-like risks. more than a quarter of Americans have no retirement savings at all, and the 401(k) balance for near-retirees often falls well below $100,000.
but it's the logic of the argument that is faulty: declining birthrates also hurt private markets, which rely on a growing workforce just as public pensions do. do you think finance is somewhat magical? if there is no growth also the financial markets won't grow. pensions shouldn't be about growth, but they are mainly about redistribution.
if we dismiss public pensions as a ponzi scheme, then by the same logic, private plans—completely at the mercy of market swings—could be called ponzi too, except they often leave those who earn less with nowhere to turn when things collapse.