I read a lot of different posts in this forum about when cryptocurrency replaces fiat money, and thinking about it I had more and more questions about how the world will work without fiat money. And some questions really bother me, as I still do not see any obvious answers to them. Suppose that Bitcoin has become the dominant currency in the world and all other currencies have simply disappeared. What should people do if in the event of a cataclysm or natural disaster people are left without light? Moreover, whole cities and regions may remain without light. Suppose that the light in these cities can not be restored quickly. How will the purchase of goods, food, money transfer? Or another situation. The world accepted Bitcoin as the main cryptocurrency, miners pooled and formed a monopoly syndicate, and raised fees for transferring funds. I do not know how technically possible this is, but this question worries me. If you have answers to these questions, I will be glad to hear them.