Basically Bitcoin is a digital currency and also an asset.  Anyway Bitcoin isn't going to replace fiat fully. Bitcoin makes our transection decentralized, secured and anonymous. It's an alternative currency which have a lot of advantages than fiat. And we all know that Bitcoin has some limitations like we need electricity to use it and old people and kids can't use it properly.
So I am totally disagree with this line and I don't think anyone is against fiat. We should take advantages by using the features of this Digital Currency and also can make profits by holding as an asset.