The received wisdom in the crypto investor crowd is that fiat money and governments and central banks are bad. Many are hard money advocates. Certainly anyone who as read and agreed with The Bitcoin standard is. In that book, Saifedean Ammous makes a case for a hard money standard being reinstated and Bitcoin being its basis instead of gold this time.
I don't think Bitcoin maximalism is a good idea. Or even that a singular hard money standard is a good idea. The obvious drawback of it is that Bitcoin is privately owned and highly concentrated into the hands of a small group of early adopters many of whom are anonymous. Suppose Bitcoin replaced all broad money including cash, certificates of deposits, treasury bills, bank accounts or any financial asset easily convertible to cash. (I wouldn't include all so called marketable securities (usually included in broad money) into that because Bitcoin is not designed to handle that type of transactions.) That would mean Bitcoin could still be worth potentially tens of trillions of dollars. I don't think rewarding a tiny group of early miners with that kind of wealth would sit well with anyone outside that group.
I have no idea how valuable Bitcoin will end up being in the future but it seems obvious to me that its dominance in the crypto space will gradually decrease with the introduction of new crypto assets.
A rigidly inflexible money supply in a growing economy would be the equivalent of a heavy tax paid by all value creators to the holders of that form of money. There is no way anyone will pay it if there is a way to avoid it. The world will always have multiple forms of money, each fulfilling the basic functions of money according to need. Bitcoin has a future as a savings technology or digital gold. But I think Bitcoin maximalism only stems from either wishful thinking or ignorance.