It's okay to doubt but you have to also know what you are doubting then that makes your doubt make sense.
Innovation and evolution is what we strive for as humans. Doubting bitcoin probably tells you lack an aspect of innovation, very soon fiat currency will be gone, digital foot print will take over. Just like AI now.
I disagree with you; fiat currency will always continue to be here. Even if there is rapid acceptance of digital currency, fiat still has a place and will continue to be here. Aside from it having something to do with our economy, not everyone out there can make use of digital currency. Even with the traditional banking system, they still don't; they prefer to go with cash unless you are proposing a total collapse of a system.