We need both of them, both of them have their own good roles and each have their own weaknesses.
Paper money would be great for real-life use, such as buying things at a price that's easy to determine.
Digital money is very good for use in digital life, it is very difficult to transact with paper money in cyberspace, even managing it for a bank is quite difficult, digital money looks simple because it only requires a wallet.
Both are different platform and I see still usable in our life.
Fiat money is so popular and As payment method.
Digital currency is digital asset and also good for payment method at the coming future.
Both will exist for along years , I think won't replace each other.
Because fiat money is usable for offline transaction , not only online.
Digital currency for online transaction, need internet connection.
We know that,
not all places have internet connection, this is the reason fiat money is still needed.