I look at it from a different angle. [Not disputing that some will make a lot of money with the bit currency craze.]
Rather, I would be leery of any country who would go the full electronic currency route, which many continue to work for. I don't like social-credit scoring, as we see growing in Commie China.
Having something be 'secure', as block chain can be, and actually having someone be able to utilize it, are two different things. Doesn't matter if someone turns $10k of digital currency into $1 million, if a credit system is established and they can't use it due to their views and actions not abiding by technocratic dictats.
Also, just from an IT perspective, it really won't be all that hard for those who control segments of digital data communication to look for digital currency moves and block/restrict it. Governments will be able to play games in that area.
I'm not a big gold/silver bug, but cash and hard metals are things that can be used in a barter economy, especially at the local level, should the "SanFran excrement" hit the fan. Can't be tracked/blocked.