I guess, if you're thinking in USD all the time. I've gotten to the point where I just think in BTC, it happens after a while.
Ok, so how much is one bitcoin worth at this moment in USD? You can't know that for sure since the bitcoin value changes so much and so fast. The bitcoin price can change a lot within a single day! While the price in U.S. dollars can remain stable for months.
My point is you're too attached to the USD.
For example, I see on bitmunchies that I can get a fancy condom for .18 btc or so. I think that's a good price. I have no idea how much that is in USD right now, but it doesn't matter.
Ah, now I see your point. That would require that the person would be very used to bitcoins. In practice it would mean that bitcoins would be more important to the person than the other currencies he or she used. In the future this situation may be valid, but today when people are much more dependent on other currencies it would be difficult for them since the bitcoin value changes so much in comparison to USD, GBP, EUR etc.