Bitcoin is a fiat currency
But that is not my point. Bitcoin supporters don't support bitcoin because the alternative is "government-issued currency that is not backed by a commodity such as gold". They support bitcoin because the "fiat" alternative has certain consequences in the real world such as being subject to the arbitrary whims of a government.
Yet the existence of hard forks shows that bitcoin is subject to the arbitrary whims of a nebulous group of people. Therefore I don't see why it avoids the downsides (as they see it) of fiat currency.
If you want to says something else regard some other statements then you need to reply to the correct message so the author can see it. The whole rest of your message makes no sense as a reply to my answer.
Thats the next best definition I could find Bitcoin doesn't fit in there at all.