When I was 60 I received a letter from the SS detailing what I had paid in over 40 years and what I was eligible to take out beginning in 7 years. By my calculation I would get back in nominal dollars what I paid in if I lived to 104, sans interest, of course. Note: I have been self employed these 40 years and, as such, have paid both employer and employee share of FICA (15.3%).
I know that, even if I survive to 104, that this is the worst investment I have ever made, and would happily take today 1/2 of what I have already paid in a lump sum in exchange for opting out of the system going forward. The government will likely means test me out of my benefits anyway when the fiscal reality becomes an exigency.
Your point made concerning rates of return in the private sector is excellent. If the American worker knew how much wealthier they would be if they had been paid the full value of their labor, then invested the part confiscated by the government, there would be an instantaneous revolutionary impetus.
The SS program has been the biggest wealth destroyer in history and now it is just a matter, for most people, of getting their share of the rotting carcass before there is nothing left. Anyone in Washington that has ever seen the budget knows this, yet they are too craven to do anything about it.
We are doomed if there is not an awakening. The realities of the fisc cannot be neglected forever.