UK law enforcement will be able to destroy a crypto asset if returning it to circulation is not conducive to the public good. Privacy coins, for example, are a form of cryptocurrency that grant an extremely high degree of anonymity and are often used for money laundering.
Fiat is even better for money laundering but sure, lets blame privacy coins. After the government has stolen- I mean confiscated your privacy coins, I am sure the world will become a safer place for banks- I mean the public.