Well the way I see it, bitcoin isn't really a currency; Bitcoin is an investment. I mean, think about it! When the idea of what bitcoin was going to be was being formed, it didn't become something that you go out and buy you groceries with, its not stable enough to be that. I mean, you could be looking at the prices of things in the grocery store and think you have enough bitcoin to pay for it but by the time you get to the front of the line, the price could have changed and you won't have enough to play for what you need. That is why bitcoin isn't going to ever replace something like the euro or the US dollar because their price change is slow and predictable, Bitcoin is something you buy in to. you spend a bit of money on some of it and then hope for a return, like the stock market. So hopefully one day bitcoin can live side by side other currencies and be something that everyone enjoys, but it will never replace them.