[Ratufa]

Your scenarios, while technically accurate, leave something out. Here's another version:

D) Your child spends his/her high-school years mowing lawns, doing part-time jobs, etc, in order to save some money to help pay their way through college. You encourage them to do so. The money earned is put in a jar. You take that money, replace it with an IOU, and use it to pay for household expenses along with more frivolous things. Now it's college time and you scramble to find the money to pay the IOUs.

[ataggart]

True, but there's an easy solution: take out a loan in your yet-to-be-born grandkids' name.

[encoderer]

...after all, they benefit by their mother/father having a college education......

[jimmyk]

I suppose you have no problem with the underlying assumption in this scheme, which is that adults should be treated like children.

[jbooth]

I think government t-bills are a little more reliable than a hand-scrawled IOU note in a jar.

[alex_stoddard]

Maybe for an independent investor. But how can a t-bill be an investment for the government itself?

I am naively assuming that what backs the value of a t-bill is the US government's ability to accrue future tax revenue to pay it back.

What is it that makes a t-bill owed to Social security an investment rather than a tax deficit when it comes time to cut a social security check?

[jbooth]

What backs a t-bill is the "Full Faith and Credit of the United States Government". Along with smaller amounts of gold, it's the foundation of most countries' national reserves, yes, "most", notably China. If the US gov't defaults, social security getting paid back will be the least of our worries.