I think the biggest cost to sustaining fiat is the power of the sovereign that backs it up. To a good extend, you have to also account for the military that secures the borders as that which also supports the currency.
> the biggest cost to sustaining fiat is the power of the sovereign that backs it up
That government and military also safeguards a lot of the economy any financial system, traditional or crypto currency, needs to drive it. In any case, sovereign-less free banking happened [1]. It was replaced for reasons of efficiency.
That will be true for cryptocurrencies too. What special loyalty does some thing like bitcoin command?
The day bitcoin has its top 1% people(By many a definition they are already there) you will need a military to force it on the people, else they can start their own currency turning the value of existing cryptocurrencies to 0.
That government and military also safeguards a lot of the economy any financial system, traditional or crypto currency, needs to drive it. In any case, sovereign-less free banking happened [1]. It was replaced for reasons of efficiency.
[1] https://en.m.wikipedia.org/wiki/Free_banking