I can believe in fiat at this time but in the future I can not because we are using smart devices in the digital world and we can use payment tools online such as bitcoin, altcoins for it. I feel easier ans faster than fiat. it does not need much private information or verification on payment and It's easy to transfer money to another one .
as time goes by i believe the time for bitcoin will come soon.
not for now , too early to say have no believe in fiat since we have spend money for daily needs in cash , not digital currency. in the next 10-20 years it might can happened. even bitcoin can be an international currency.
Ver unlikely to happen that bitcoin will become an international currency, governments can
make digital currency that can rival bitcoin which is likely to happen if they implement a digital currency.