Two different situations - cash from cash businesses vs. emergency cash. Reading between the lines, I think the OP was talking about emergency cash. As others have noted, in a true national emergency cash may have value for only a couple/few days given what's happened in other countries over the past hundred years. Also as others have noted, that cash depreciates over time, and would even faster in a grave national emergency.
Hope someone will enlighten me if I'm missing something, but the only use I can see for that amount of emergency cash is transportation - either (1) buying transportation and fuel immediately upon the onset of a national emergency or (2) to quickly disappear, get transportation (private plane(s)?) somewhere, and start a new life if one got crossways with the wrong kind of folks. That's probably about the amount of cash needed for the second scenario, but I try to avoid the kind of folks that people run from.
23yrs ago, big flood in Grand Forks, ND, 50K people mandatory evacuated. My friend owned an essential business and stayed. Due to the flooding, most of town had no electricity and those few businesses that were deemed "essential" and were therefore open, were only dealing in cash as electronic payment methods were sketchy due to the flooding. My friend ended up having to drive 50Mi one way to the next town to find an ATM that would dispense. Everything in town was either out of cash, or unable to communicate.
I know I don't know enough about "Doomsday Scenarios" to know how to be prepared for the end of days, but, some cash on hand to buy a week or 2 worth of groceries or a full tank of fuel sure seems prudent. In fact, I think it's foolish to travel without enough cash to at least buy enough gasoline to get yourself home, wherever that is.
