It is said that bitcoin will destroy the fiat system but i believe that if this happens the world will change completly because banks and a lot of things will go out of market.
up to now it's still unpredictable if bitcoin will be used by most people around the world in the year 2020, 2022 or so. also it is very unlikely for bitcoin to destroy the fiat system bitcoin because it's price is still depending on fiat and if ever that happens the government will surely be so eager to take in control of the bitcoin system and they will end up to impose a much higher taxes on it .