You could really say the same about any fiat currency. They are all just units of value we use to exchange for goods or services at a later point. Now, Bitcoin is a lot more volatile than most fiat currencies so that is where the distinction really comes into play. If you woke up tomorrow and discovered that the savings in your bank account could only buy 80% of what they bought yesterday, you'd likely be very annoyed. It can go up in value as well, but people generally like stability and consistency. I have a feeling that for Bitcoin at least it will improve over time as the amount of holders goes up and this should bring the volatility down. It's actually rather useful having a global currency that does not have to sit between the whims of local exchange banks.