I think that the "greedy geezers" are going to last a lot longer than you may realize.
Today's Social Security benefits are being paid from Social Security contributions by employees. There is apparently a net surplus beyond what is required for present benefits. That surplus is then loaned to the Federal government in exchange for these special-issue bonds. The government then spends the cash, every thin dime of it.
This has been going on long enough to have built up a "Social Security Trust Fund" consisting of 1.5 trillion dollars in bonds. There is no cash in this "fund".
It sounds as if much of the public national debt is owed to the Social Security Trust Fund.
At some point in the future, contributions to Social Security will be less than benefits being paid, and it will be necessary to begin redeeming the bonds in the "Trust Fund". To do this will require taxing the public at a higher rate than otherwise to pay off the bonds, or selling some other debt instrument to raise the cash.
The important point is that every single dime which is paid from the Social Security Trust Fund must be raised by taxes or creation of some other debt. There are no dollars there. The only "assets" are bonds, which are just government IOUs.
The liberals are careful to downplay the significance of the fact that public employees are NOT participants in Social Security. And that any private company which created a program, funded the way Social Security is, would be guilty of criminal conduct.