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!
So because different currencies have varying exchange rates with one another, they aren't currencies? Nonsense, all currencies do this with one another, bitcoin simply has more volatility because it's so knew, and most people haven't figured out how valuable it is yet.
Ok let's assume you get a bitcoin back. Which is now $300 all you have to do is sell it for $300 and pay 3/4 of for the pair of jeans. Which mean you made $50 on this transaction. How ridiculous is that?