FIAT money is our daily currency which has been existing here for hundreds of years, when crypto currencies like Bitcoin is squeezing their way up to become a world currency and sort. Can they co-exist? If so then what benefits we can get from them, altogether? Not separately.
Maybe next in future if both fiat and bitcoin can be used for daily life, it will not disrupt each other. Because they will have their own user and it all depends on merchant which accept it. But for price, it will make bitcoin price increased.