I think in the real world you cannot really establish intrinsic value of something since that value depends on human reasoning.
What you perceive as valuable can change depending on your mood and the mood of many people can change failry quickly.
Even if you try to use mathematical sound equations to determine value, people can disagree with these calculations and act irrationally contradicting your consclusion about the price just to piss you off.
One announcement of the government can change the value quickly because economics is in some sense faith based. If people trust the system there is going to be more value in it then if they don't and faith is rather volatile.