The loss of control is essentially equal to the death of the state. In addition, given the factor of influence of monopolized miners on the volatility / rate of bitcoin, such a "currency" can simply kill the economy from deliberate or unintentional actions of monopolistic miners.
And finally, the use of a deflationary currency in the economy, from the point of view of economic competitive advantages, loses to the deflationary model.
I believe governments can use this to their advantage as well, but they seem to be not doing something like that. Contact the biggest miners, get them to a room, talk to them about how much they can save, like get over 10 billion dollars of bitcoin saved, pay their costs, then when they have 10 billion dollars worth of bitcoin, tell them to all dump them at the very same time all over the crypto markets, just keep dumping more and more in top 10 exchanges constantly until the price is very low, then cover their loss from what the start price was and what the end price will be.
This will be at most few billion dollars, big governments call it a half a day worth cost, USA printed over 5 trillion dollars just in the last year, few billion dollars is nothing. So, we can't just come out and say "can bitcoin kill central banks", if central banks wanted it, they would have killed bitcoin in a day.
And what is the point of such steps? Banks can simply prohibit operations with exchange accounts, thereby effectively stopping the operation of converting crypto to fiat. This means that the majority of crypto users will not be able to make purchases for fiat. There are very few points of sale for crypto now, and they definitely do not cover even 1% of the needs of the population.
Ninado no spending, no negotiation. Just blocking accounts. Or they will make an even more interesting option - withdrawal to fiat will be possible through trusted banks, which will preemptively remove tax from the withdrawn amount
Well, the question about the Chinese miners, who are monopolists today - do you think they will actually negotiate, where the result will be a drop in the price of the cue ball? Moreover, this is China - a country with a rather specific policy, and its own interests