The circulation of gold currency is currently a minuscule value compared to the entire economy. This fact would place pressure on the volume of gold liabilities in circulation if it were not for the fact that there is a serious opportunity cost for exiting the gold economy. That opportunity cost exists because it costs money to enter the gold economy. That doesn't mean people can't remove their value from the gold economy. It just means that there are always going to be others who contribute the capital to maintaining the gold in circulation.
Market Makers are people who buy gold in order to sell it for a profit.
These individuals and businesses ensure that there is a stable circulation of gold in the system by purchasing gold from those wishing to exit the system. Then there is the trust issue. The gold economy is predicated on the idea that every transaction is a cash transaction. The operator of the transaction system will not reverse transactions. Additionally, every transaction is settled immediately.