>You can’t conclude that if you spend it, then it is a currency.

Why not? It's an abstract concept. Consensus decides whether something fits the definition, or even change the definition so that it fits. And, IMO, if WoW gold is widely accepted to be a currency, then BTC is too. YMMV.

My point refers to those who still bang on the fact that you can't pay BTC directly to buy bread, therefore it's not a currency. Just because it's not used in the economies YOU engage in, doesn't mean it's not a currency. You're just not involved with it.