There is a world of difference between gold and Bitcoins. Gold was always valuable in itself, before anybody used it as money, people wanted it just because the metal was fairly rare and easy to make jewellery from. It's not like gold was found and immediately people said: that's money. No, gold was a metal that was desired for thousands of years, then eventually it was used as money also for thousands of years. Gold was storing value for people before people started commonly using it as money, the metal proved itself to be capable of withstanding the test of time in business of storing value.
Bitcoins were intended to be money from the beginning, their entire existence is for one purpose: to be money. In that sense Bitcoins are a currency, and since they are not backed by anything (no gold behind Bitcoins), they are a FIAT currency. The difference is that they are not printed by government, but the scarcity argument is moot, every bit of Bitcoin is about as 'valuable' as any other bit. One Bitcoin is essentially 10Million coins, each one can take an arbitrary value. More importantly, competing electronic fiat currencies exist and there will be more and more of them as more people want to participate in this new electronic currency market.
To say that Bitcoins store value is premature AT BEST, I don't think Bitcoins will become less volatile with time, I think they will be more volatile with time, I don't think they store value, I think they are an interesting vehicle for speculation and many disciplined day traders can make a killing trading these, but there is no value outside of its direct purpose: be currency.
Some say that the protocol and the network are the value, but again, those are replicated across many other currencies and there will be more of them, there is nothing special about Bitcoin except for it being first, but being first also has disadvantages. With Bitcoin prices going up, every time the price goes up, the risk that one takes buying them is bigger than the day before. There was very little risk buying 1000 Bitcoins at a few dollars a few years back. Today to buy 1000 Bitcoins you need half a million or more dollars and given the speculative nature and volatility, very few people will buy 1000 Bitcoins, but they will buy a few or maybe fractions - coins of smaller denomination. Or maybe they'll buy other coins, that are perceived to be cheaper.
Basically declaring that Bitcoin is a store of value is extremely premature but also is most likely completely false.