It's hard to make Bitcoin a currency because Bitcoin has so many disadvantages that it's hard for anyone to use it as a common currency. Bitcoin's pricing is also a big drawback.
It is true that the volatility in the price of bitcoin is a big drawback for those that want to use bitcoin only as a currency, but besides that the only two other disadvantages that I see that bitcoin has is the speed at which a transaction is confirmed and the fact that you need a computer to access bitcoin when you do not need a computer in order to use cash.