Just one point to add: there is no currency that is universally accepted. You probably cant buy a pizza with Kuwaiti dinar right now either. But that’s definitely a currency. So your part about “everyone agrees” is not really true of any currency. They work only for a subset of humanity who mutually agree it has value. And you can absolutely find people who will buy crypto from you using other currencies, or give you goods and services for it. Those people are rather randomly distributed around the world though instead of being grouped inside one geographic border. That’s the only difference.