Me and my colleagues ask if it is permissible to use the currency and they said it falls in the section where doubt is. In Islam doubt should be avoided but they never prohibit us. We said we work and earn money from a site where they pay us via crypto. Their answer it is okay as along as we are not with the ones who are in the deceiving team or scammers, it is okay for us to use the currency as long as no harmful effects to other folks around us. They say that even the paper money does not have a value but it said to believe it has, so there shouldn't be a problem in a digital one. We may never know, sooner or later Muslim countries like Dubai or UAE countries will use a digital currency and disregard the paper one.