Part of my original point was that currencies don't have "missions", people do. A person may or may not wish to own a bitcoin in order to facilitate transaction

Part of my original point was that currencies don't have "missions", people do. A person may or may not wish to own a bitcoin in order to facilitate transactions. A person might also wish to own one as a speculative investment. Neither "mission" is necessarily better than the other. Krugman just assumes otherwise.