Social Security is unsustainable because it is not meeting the first order condition of a Ponzi scheme, namely expanding the pool of suckers. Social Security has been one congressional lie after another since its inception. Here's what a 1936 Social Security pamphlet said: "After the first 3 years -- that is to say, beginning in 1940 -- you will pay, and your employer will pay, 1.5 cents for each dollar you earn, up to $3,000 a year ... beginning in 1943, you will pay 2 cents, and so will your employer, for every dollar you earn for the next 3 years. ... And finally, beginning in 1949, twelve years from now, you and your employer will each pay 3 cents on each dollar you earn, up to $3,000 a year. That is the most you will ever pay." The pamphlet also said, "Beginning November 24, 1936, the United States government will set up a Social Security account for you. ... The checks will come to you as a right."
That's another lie. In .Flemming vs Nestor (1960), the U.S. Supreme court held that you have no "accrued property rights" to a Social Security check. That means Congress can do anything it wishes with Social Security. There is little or nothing that can be done to prevent the economic and political chaos that will result from the collapse of Social Security.
Today's recipients of Social Security, along with their powerful AARP lobby, represent a powerful political force. Few politicians are willing to risk their careers alienating today's senior citizens for the benefit of Americans in 2040. After all what do today's seniors and politicians care about a 2040 calamity? They will be dead by then.