For example, any real estate with a premium for its "better location," suits by Armani, sunglasses by Gucci carries a similar premium. This applies to gold as well--a huge part of the value is the expectation that others will continue to like shiny things.
Nothing anchors their price, or premium, other than a system of social beliefs and expectations. Specifically, beliefs about how others will perceive them are all crucial in how people value these items.
The same is true for bitcoin. It starts with a belief that others will also prefer to store value in currency with a higher utility--storable with no fees, and instantly transmissible lower fees--lower friction. It isn't so much the greater fool theory as it is the starting of a journey toward a Nash Equilibrium. But first everyone has to come to a belief about how they, and others view the currency. http://en.wikipedia.org/wiki/Nash_equilibrium
Once this has happened and additionally the markets have become more liquid, things can level out. Right now, the world-brain is confused about how it feels about bitcoin.