[alkonaut]

I’m not (only) talking about things like fractional reserve banking and central banks, but of regular nation states that can collect (and do succeed in collecting) taxes.

Bitcoin can simply be banned. It’s not that complicated. Note that the ban wouldn’t be on the tech itself, mining or possession. It would simply be a ban at the points of contact with the regular economy. Basically you can’t exchange currency, goods or services for BTC.