There's a lot of reasons why people prefer to use the btc over fiat.
I think one of their reason why they stick to btc, its because btc has a lot of great features than the fiat and its also much more profitable than the fiat.
I get your point of thinking, but it is not like that in my opinion, because with fiat u can pay basically anywhere, without any problem ( unless you have wrong currency ),
and with bitcoin, you can only pay in few stores so we need to take some time before saying things like that