USA and Iran can be the main cause to triggers world war 3 but i think most of countries in the world don't want it and they will prevent this from happening because if this is happen then it could be the biggest war ever in the history and i think if world war 3 happen then no more crypto users because the impact for majority countries will be so huge although maybe not all countries involved but from economy side it will resulting in a global recession
Not only will the global economy collapse if a large-scale war is to happen. It will also impede with technological progress as the manpower required to carry on technological progress will then be allocated to arms race. And since bitcoin's heart is the internet which needs constant maintenance, it is highly likely that bitcoin will die if a war were to happen.
If there will be a war. There will be still internet because it is the primary source of information and communication for every country. Bitcoin will not die because of war, it will prosper instead because of the demand that bitcoin could get when people panic about saving their wealth through the power of bitcoin and its decentralized system.