The way I have usually seen this expressed is that you take funding that would otherwise go to support/welfare programs, and use it to fund this. The problem becomes one of who is responsible if the particular investment fund/vehicle doesn't perform well enough to even pay back the original $10K? If it's going to be Government directed, then what the US buys and sells becomes a bit of a market mover, and you have to invest "against" that to have any hedge if the person running the US fund guesses wrong.

This has also been proposed as a way to get out of the Social Security "mess" that is heading our way.

Not saying it couldn't be done, but haven't seen the idea ever get much traction.