Sam sees the flaw in his own argument - when he mentions gold and the possibility of its use a store of value. But he doesn't understand the full significance of his own comment. Moldbug has by far the most compelling (imo) theory on the origin of money and why bitcoin (and gold) float far above their use value. These two posts cover it very well:

http://unqualified-reservations.blogspot.com/2011/04/on-mone...

http://unqualified-reservations.blogspot.com/2013/04/bitcoin...

I highly recommend them to anyone trying to understand the economics of bitcoin