oldfart
Older than dirt
It's not like a bond at all. You are "forced" to pay into SS, unless you are one of the few lucky folks who are exempted. You don't "own" your SS, you can't sell it, you can't transfer it to your children in your estate. For many people it does not earn interest, in fact for many they loose half the money they put in. Hell for some they loose all of the money they put in. Further for each subsequent generation it has cost them double the amount of income to fund SS than the previous generation paid in by % of income. Thus it's not like a bond at all, from an investor's perspective it's more like a government mandated ponzi scheme. From a social perspective it's nothing but welfare for the masses. From a realist perspective it's just another failed experiment in socialism.
If your main objection is that it is possible for some participants to receive less benefits than they have paid in, private annuities provide an answer. With an investment annuity, you can pay an extra premium and the insurance company contractually guarantees that you will get out at least what you paid in. It's called a refund feature.
So if this is a big objection, why do insurance companies not offer Social Security refund insurance? They would get the extra premium, and would only pay off if the sum of retirement, disability, and survivor benefits paid by Social Security did not match the amount paid in. There is no legal impediment I am aware of that would prevent his type of plan, you have insurable interest, etc.
The obvious answer is that there is no market for it. But if there is a market, I propose that we form the USMB Great Insurance Company to offer the product. You and I, Kimura, Toro, and a few others could get it off the ground, and if there is a market, we should be highly successful.
Alternately we could lobby for a bill to add a refund feature to Social Security. Would you support such an effort?