-snip-
Take a look at it from the outside, as if you weren't American. Who stands to win from a shutdown, from welching on US govt obligations?
Holders of US securities, that's who. They're the safest investment in the world, and the backbone of nearly every great portfolio in existence. OTOH, yields are currently dismal, driven by strong demand for them. Every rollover of old bonds for new gives lower yields.
What to do? Create a situation where their safety is brought into question, forcing yields up. Better yet, do so under false pretenses of defunding the ACA, a proposition driven by the ideology of smaller govt at any cost. You have an army of such idiots at your disposal, so keep 'em whipped up in an emotional & ideological froth. You also have the fact that the Repub leadership is scared to death that the ACA will actually work & be popular. They're very, very heavily invested in preventing that from happening. It would body slam their whole ideological premise into the dirt.
Oh, yeh- Use derivatives to bet on failure, even as you force it to happen, and nobody will be the wiser, either.