Taking a step back, first decide what you need to prepare for:

The 'good cop' of the internet: Wikipedia, is always a good place to start.

https://en.wikipedia.org/wiki/Nuclear_holocaust

Covers the likelihood of a nuclear holocaust. And whether you need to prepare for EMP, nuclear winter, starvation....

From the little I've seen of preppers sites they seem nonsense. I've yet to see one (though as I admit, I've not seen many) with a radiation detector in their kit. Surely item number one if you really think some areas are going to be certain death if the wind is in the wrong direction, whatever you do.

As for the dollar becoming worthless; it sounds absurd. The US dollar is the worlds reserve currency. The arabs struck oil, you struck everything. You are a manufacturing, finance, academia, techological, computing, agricultural, fisheries, timber, oil, coal, gas, gold, silver etc, etc giant. A huge (330 million) skilled and educated workforce. A military that could probably defeat the rest of the world combined. You spend as much as the next 10 countries together The count of countries the US has invaded keeps growing. The number that have invaded you has remained the same since 1812; zero.
how could that possibly happen?
qjs