Pretty simple, if you're from a region that has conflict, you're better off with fiat
Actually in case of that what you need is food and shelter because neither fiat nor bitcoin are going to prevent starvation or stop bullets.
Not to mention that you can't really store large bags of cash in your home because the banking system is going to be the first that will get hit. You can see how Russia performed a large scale cyber warfare against Ukraine over the past couple of days that included hacking their banking system. Meanwhile bitcoin is not and can not be affected by this.
It all depends, I think that Fiat is most likely to be important at a time like that. And why I think so is because despite what you will be needing is shelter and food, you would still need money to purchase food and to pay for shelter, although that really depends in some situation. But, mostly you’d be needing cash and that is what most people would think.
But that doesn’t make Bitcoin any less important, they are all good, and I don’t really think it is that much necessary for anyone to be selling their Bitcoin unless maybe you do not have much money in your bank account and you feel that you need to sell some of the bitcoins that you have to kind of cover up for what you are lacking at the moment.
And I also do not think that people would have time to be selling Bitcoin in such a time, their mind wouldn't really be going there for now 'cause they would just be looking for ways to survive and that's it.