Actually you can argue exactly the opposite - when you are surrounded by devastation with no water, electricity or maybe even food - then it is highly unlikely you'll have access to an internet connection that could allow you to move such crypto funds around easily. Cash is king in that scenario (provided it's not the Russian ruble) but more likely things like gold are useful for bartering your way. Most of the world is privileged to exist in a relatively stable environment, but the sheer devastation that has been wrought on parts of Ukraine mean that it's much easier to transact in physical goods and makes hard cash more important than ever, provided it is relatively low volatility like USD.
I have read the stories of people that had to survive during a war for months and even years, and stuff that has no utility very quickly losses any purchasing power and you have to either barter or offer some useful skills that you may have, stuff like food, alcohol, medicines, toilet paper, cigarettes, candles and other consumables become incredibly valuable, while cash and gold become useless, now if you happen to accumulate a lot of cash or gold and survive the war you could make significant profits, but under those circumstances most people only think about the short term, as they do not have any idea if they are going to live to see another day.