What good is physical fiat in the same warzone? If anything that use case scenario is the one for gold/silver, food rations, water/purification means, and a stockpile of bullets.

That all said, if I'm trying to get OUT of that warzone, I'd sure rather have my 12/24 word phrase memorized, or perhaps a bolt with washers that have it stamped into them, than be trying to figure out how I'm getting across borders with physical cash or even gold. It worked for Afghani women who otherwise lost everything escaping the return of the Taliban, which is proof-of-work enough for me.

There's room for some diversification if done thoughtfully, for sure, but the amount I'd bother with in actual fiat cash is next to nothing, because nothing says it'll hold any value in that scenario anyway. 

 I mostly agree.

However I'm quite sure that ppl will accept cash even in wartime. They simply believe it has a value (don't ask me why, idk). For some time at least.