IMHO it's not the right way to think of bitcoin in this fashion. Though I'm sure that 99.99% of BTC buyers/sellers nowadays are interested only in the value of BTC in FIAT currencies as they hope to exchange it back into FIAT when it will reach some "FIAT" value. But I believe it's just temporary hype and with wider adoption by merchants people will consider BTC a real currency and they will use it for buying stuff instead of trading it for some worthless FIAT currency which BTW will lose its value more and more in the future (for its nature). I think that selling BTC for FIAT is just waste of BTC.

The value of BTC is the stuff you can buy for it and how much do you value it for yourself. For most people that stuff is some bullcrap FIAT currency, but it will change, trust me