How many merchants, sellers and producers are actually using Bitcoin or any other coin as a means of exchange right now? No one, in fact, at least not in any significant degree. And the explanation is simple, all these people need a stable currency but since the modern economy is not stable by any measure or in any frame of reference, it needs fiat with its built-in mechanic of automatically regulating and adjusting the money supply according to the needs of the economy, so that it would be dynamically stable (like a roly-poly). This supply includes not only money itself as we are used to think of it but also other highly liquid instruments which are effectively money derivatives and can function as money, while being created and destroyed on the fly as required by market participants and economic entities like banks. 

Now imagine what catastrophic meltdown is going to happen if Bitcoin, by some magic or miracle, becomes the only medium of exchange in the whole world. It will wreak total havoc through the economies. It is definitely not about some people being very stubborn or anything like that. Fiat is in fact the only viable option to keep economies ticking, whether you or someone else like it or not.