That one's always bugged me, because it's easy to imagine a Keynesian household budget, too. Imagine a multi-generational household where the patriarch has savings but where the living expenses are covered by his descendants. Then the banking system go crazy for a couple of months - a kid has a business idea that will make money but has lost bank funding. The patriarch has the choice whether to invest savings to get the business off the ground (increasing the probability of the kid contributing to living expenses in the future), or instead just tell the kid to tighten his belt, at the expense of the patriarch's own future living standard.

There's always the risk of voluntary default; either the Republicans are bluffing on not raising debt-ceiling, or they aren't.