Take a breath.
I more or less agree with you that “the economic collapse of the United States” is more or less a foregone conclusion, but it’s not going to be headline news in the paper some morning that says, “Money No Good; Debts To Be Repudiated”.
It’s a slow-motion thing that will take years and years to occur, and even as it does occur (or is occurring, if you want to look at it that way) there will still be a stock market; there will still be supermarkets and farms to supply them; there will still be roads and bridges and interstate commerce. Life will go on.
Look at the collapse of the Soviet Union, for example. That country was nowhere near as rich as this one has been for more than a hundred years, and the collapse of their government was nearly complete. But you still didn’t hear about mass starvation and rioting in the streets (for the most part, save for the skirmishing around the Russian White House, which involved soldiers and politicians more than the average Ivan).
Relax. Order the seeds, though, and plan that garden.