There is a respectable case to be made for cryptocurrencies. They offer a store of value that is independent of governments and central banks – which is partly why they are associated with economically liberal or libertarian politics.

But there is, equally, a case to be made that cryptocurrencies are a form of Ponzi scheme; that they have no intrinsic value and therefore rely on a kind of confidence trick in order to work.

There are other reasons for being sceptical about digital coins, including the anonymity they can confer, which makes them useful…