Money is several things - including a store of value and a medium of exchange. You can see how Bitcoin could be both of those (just about), but the example of Greece and the Eurozone demonstrates the undesirability of separating fiscal and political power. Once you separate them, in economic terms, a national state is reduced to the status of a household - which might be easy for voters to understand, but isn't necessarily good for them - unless you happen to like being ruled by the Germans (nothing against Germans by the way, it's just that they have the dominant European economy, so they call the shots - plus ca change...).