I have taken my time to understand how government can kill the existence of cryptocurrency. I did not see it's feasibility. Govt can only discomfort the users by enacting laws that will outlaw the existence of exchange houses and disconnecting their relationship/transactions with financial houses. Thus, those who have cryptocurrency will exchange them for goods amongst themselves, and settle debts amongst themselves also.
As for throwing it out of circulation is impossible. It is more private than public.
Good expository. Upvoted