Maybe all of Greece won't be using bitcoin as money any time soon, but what are they going to use? One of the major monetary properties of Euros in Greece just got removed. It's kind of like having money. Kind of.
Even if it officially reverts to the drachma, they still border plenty of countries using the Euro and it has far more utility. I assume it'll be like so many other countries in the world. The local currency runs in parallel with the more useful one.
That's other people's money you're talking about, I was asking how they're going to use the "money" they have in their bank accounts.
