You make the case about as well as it can be made. But there's a few problems. The raw amount of transactions in gold is necessarily small. After all, to really transact in metals at a distance you have to pack a lump of metal in some packaging and mail it. Bitcoin is greatly advantaged in this respect. But it is not advantaged with the blessing of the periodic table, people laugh at altcoins, but they really are the competition. They do what bitcoin does, just with less liquidity. To just wave your hands and say "Network Effect" is not sufficient to equate it with a rare, dense, non-corrosive, and shiny when polished metal.