> Well bitcoin is as much money as FIAT money

No, it's not. It’s too volatile to be an efficient store of value or a useful unit of account for general purposes; it's got some use as a competitive medium of exchange for certain circumstances (but again not really with the generality of any major fiat currency.)

It's commodity that seems to (retrospectively, at least, and there is some reason to expect this to continue for the near future) have good investment performance if you are in a position to wait out down periods, which makes it nice as a component of an investment portfolio.

It's good at things that aren't the purpose of money, but mostly not good for things that are the purposes of money, except for a narrow subset of one of three major purposes of money.

> Than indeed, bitcoin would not be money.

Bitcoin is obviously not money, and among the many reasons the fact that it does not serve as a store of value nor a means to defer payments, which is a single requirement that comprised the very definition of money, is just one of them.

The US government would not accept BTC as payment for anything, so it is definitely NOT a fiat money.

The actual only criteria of fiat money I learned in austrian high school was "government will accept taxes in that currency". We have quiet a long history of taxes here, ranging from cows or sacks of grain to gold to gold coins to gulden to reichsmark to schilling to euro. Probably a good measure of centuries more than the US (which basically got kickstarted with the UK system at the time). Funnily enough, the above definition was the only thing holding true through the centuries. Thing is, if your government accepts taxes in a certain currency (even if it's a foreign one, that's perfectly fine too) it creates a stability by itself which fosters the usability (call it user friendlyness if you like) of the currency. In that sense, I'm fairly sure that unless you are personal friends with the president you cannot pay your taxes in Euro the same way you cannot pay them in ₿, Pesos or ¥ because the currency the US claims their taxes in is USD. Please prove me wrong or gib a better definition if I'm wrong :) Happy New Year everyone!