This is really something that should not happen at all, we know how much money we will all lose not only banks will close but even businesses, and worst thing our local currency will have no value just like Venezuela, so I don't think that people will prefer to buy Bitcoin at that time or will prefer buying golds.
We have economic crises all the time but a global economic crash is way more unlikely, however if it comes to pass most people are not going to worry about trying to buy bitcoin because their money is going to be worth nothing, at that time people are going to be worried about their survival and getting enough food and water.
It seems like a very dramatic scenario, and it is, and that is why I do not want it to happen, but if governments keep creating currency as if there are no bad consequences for it then at some point that will happen.
for wealthy people, I think they will be alert before the war, property may not be a priority to be saved, and I think in this case bitcoin will be an option, because we only need to save the private key, to access it later when the war is over. but indeed food became gold when the war broke out to sustain their lives