Comment by logicchains

>I always thought taxing money leaving the country might be interesting way to approach the problem.

Even China with extreme capital controls and pervasive surveillance can't stop money leaving the country. Unless the UK was willing to go fully authoritarian and ban its citizens from spending money overseas, and ban crypto (and build all the internet firewall/DPI infrastructure that doing so would require), it wouldn't stand a chance. And attempting to do so would destroy the value of the pound, because nobody with any options would want to hold a currency that could only be spent in the UK.