The discussions about economics applied here focus too much on microeconomic rather than macroeconomic arguments. So they end up missing the point entirely which is this:
Money isn't a neutral instrument and it's not something that can be decoupled from societal/political concepts and structures.
You can evaluate it as though it is neutral, but it has not ever been and will never be a neutral instrument because of the historical tendency for resources to pool and therefore become power centers, among other things.
Therefore if you view cryptocurrency as having the primary intention to de-couple commerce from coercive power structures [1], then you'll see immediately the historical problem. Namely, history doesn't favor distributed power, especially not when it can easily be co-opted by the powerful systems in which they rely.
In the best case scenario for crypto-utopians, millions of people transact and do commerce on a decentralized currency. In that case, whatever sovereign is most impacted, will then either outlaw commerce by crypto by force or require parity with the sovereign currency and control of the crypto currency through tax payments. This has happened multiple times over the centuries with alt-currencies and they are killed off by the most powerful (see: Most powerful economy/military) organization.
Politically, there is nothing different about Bitcoin than there was with the confederate states dollar for example.
[1] From the original whitepaper: "What is needed is an electronic payment system based on cryptographic proof instead of trust, allowing any two willing parties to transact directly with each other without the need for a trusted third party." https://bitcoin.org/bitcoin.pdf