With US bombing Iran, talks of WW3 seems closer and closer. I am, of course, not wishing for this to happen as nothing good will come out of it. But let us think for a second how will bitcoin be useful to us should WW3 actually happen? First of all, expect chaos. Fiat Currencies would most likely decline. Governments would need to print more money to budget for fighting other countries. This will surely lead to inflation. This is where crypto would come in handy. Bitcoin can be a safe haven for most.
The most important thing is if you live in a country directly affected by the war, surely people would migrate and seek shelter. Bitcoins can be helpful for doing this as you will not be carrying your country's local currency. I am sure now that people would be buying crypto in fear of the war happening.
If there will be a World War 3, I think that we are in such a grave danger that no one will care about Bitcoin or anything because nine powerful countries have nuclear weapons and some of them are enemies of each other. If there is a World War 3, I think that we will reach to a point when someone will use a nuclear weapon, then another one will answer with a nuclear strike and we will get massive nuclear bombing.
Bitcoin comes very handy in wealth transition. If you are wealthy and have to leave your country because it's getting bombed, you can't carry your house, car or anything else with you if you decide to travel in a different country but you can always carry Bitcoin paper wallet with you anywhere you go. You can sell your wealth, buy Bitcoins and move anywhere you wish but you have to do it before nuclear war starts because then nobody will care about your wealth to buy.