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.