There is always a chance that a fiat currency will crash, if the government/central bank resorts to reckless policies that break public confidence in the value of the currency.The history demonstrated that all the fiat currencies crashed at some point and they are unstable by nature - they are only backed by the government decision to declare it legal and maintain the illusion of value. It is because the inflation always jumps, the purchasing power drops, and at some point this bubble ruins not only the currency's value, but the whole economy.