Bitcoin is NOT a currency!
In it's simplest form it is just payment rails. Stop thinking about is as currency and what is left to regulate?
If a merchant selling a pair of jeans for $250 accepts a 1 bitcoin and customer 2 weeks later asks for a refund with a value of a bitcoin going up to $300. Is he going to get 1 bitcoin back or a value of the jeans he bought? Naturally, the value, which means 3/4 of a bitcoin at the time of the refund. So, how does it make bitcoin a currency. ITS NOT!
What do you think?
Putting it that way... it got me confused for a moment. But when you think of it, we only need to deconstruct your own post. If it wasn't a currency why the hell would the seller even accept bitcoin for that purchase?? Simply because bitcoin its currency as well as it is a payment system. So it's more as a commodity that has all the features to be a currency as well as a payment system. You could even think the same about gold!