Social security is an annuity, and a damn good one--it's guaranteed by the US Government. What we need is for supplemental annuities (above SS amounts) to be offered by the federal government at cost, or to guarantee annuities sold by insurance companies (a la FDIC).
Social security is fine, but there's no way to over-contribute to intentionally up your benefit. In fact it's sort of the opposite -- the more you contribute, the lower your marginal returns. If the US government allowed voluntary SS contributions that paid out on a fiscally responsible schedule that might be a good solution. But I'm not sure it would be a better one than just letting private companies implement them.
It is much easier to create a mandatory annuity than an optional one because you don't have to worry about people who have a lower than average expected payout opting out. If the annuity is optional you need to have a much more sophisticated way of determining how much people should pay.
> What we need is for supplemental annuities (above SS amounts) to be offered by the federal government at cost
The U.S. government already sells 30-year Treasuries and savings bonds [1]. Spinning up a new government program is complicated. Just authorize the issuance of 50, 70 and 90-year Treasuries.
Bonds work differently from annuities, and are vastly more expensive per desired dollar amount of fixed income (provided you don't care about your children's inheritance).
