If we take the definition made here
https://en.wikipedia.org/wiki/Fiat_money then Bitcoin is only fiat money if program code is
interpreted as being
"law". Do you agree or disagree or have an opinion on:
"
Fiat money is money that derives its value from government regulation or law."
Now if it only means law made by a government, then by that definition Bitcoin is not a fiat currency. by the Wikipedia article's definition that I quoted.
Before crytpo-currencies, the distinction was pretty clear. If the scarcity was natural, like gold's, it's not fiat. If the scarcity was artificial, like unbacked paper money, then it's fiat. Currencies that were redeemable for commodities by their issuers, even if there was a fractional reserve, were not considered fiat.
This made definitions of "fiat money" like "money without intrinsic value" and "money whose value is not fixed to an objective standard" equivalent. However, when you bring crypto-currencies into the mix, things get interesting. Bitcoin's scarcity comes from mathematical rules, but the choice of those rules and the ability to change them comes from an agreement, but that agreement cannot be as easily changed as a government can print more money.
Now, there are two ways you can react to this. There's the irrational way and the rational way. The irrational way is to parse dictionary definitions of "fiat" to see if Bitcoin qualifies. But this is irrational. If a company makes a three wheeled vehicle that acts just like a car, we don't look at dictionaries to decide whether it's a "car" or whether we must call it a "tricycle". We look at how it acts. If it works just like a car, we call it a car. And, if it becomes really popular, then we remove "typically with four wheels" from the definition of "car".
So the right question is whether Bitcoin *behaves* like fiat currencies. If it does, then we should consider it one. If not, then we shouldn't. Either way, if needed, we should adjust the definition of "fiat" if we want the distinction between fiat and non-fiat currencies to remain useful.
