Honestly their both good form of payments and asset, some people just prefers cryptocurrency because it offers something new to the table where you can freely use and control your money without worrying being traced or regulated by the monetary system, but bitcoin has the drawbacks it can't be used as payment in local businesses, not all people uses crypto. That's what fiat is good being used as physical form of transaction and people likes stability not like bitcoins volatility.
I think cryptocurrency is just futuristics and easier to use because it is portable and secured compared to fiat currency that could easily stole from everyone and also could be destroyed.
But more like cryptocurrency is not yet used since the technology needs to keep up so that it could easily be implemented in the community compared to fiat money which uses already the traditional way.