Joe does not set the price. This is not a unit-per-head market like iPhones.  The LBMA sets the price of gold, not Indian wedding planners.  The bulk transactors, the whales, will determine the price of Monero... up until the point where it has a local currency monopoly, dominant reserve status, and the standard of accounting.  Inside of a local currency monopoly, the size of the economy and the money supply will determine the value.  Joe just eats what is put in front of him.