Fiat currencies are controlled by a central authority (governments and banking institutions), cryptocurrencies are beyond their control. The government will likely take many precautions to prevent the growth of cryptocurrencies or deploy enough regulation that the digital cash system works on their terms. This is why I think crypto companies that work with the current system will do best, e.g. Plutus is a cryptocurrency payment platform that lets you purchase with crypto at 40million stores worldwide because it utilizes the existing VISA infrastructure and partnered with Contis, a fintech bank.