This is not some big currency or export program. It's most likely Grandma and Grandpa hawking their jewelry.
The cash for gold industry in the US is absolutely massive and growing. Most of it is fueled by boomers dumping their assets into gold and silver - and then cashing it out when times get worse.
Need cash on hand, pawn it or use it as collateral for a loan.
It is away around the legal system to retain wealth.
Yes, absolutely, and it goes back farther than criminals. Why do you think everyone's grandma has a jewelry collection, while less of the youth do? Because before the 70s, women were not allowed to have their own bank accounts. Their gold and jewelry was the only type of wealth they could keep for themselves.
The other reason is the Christian historically yes-and-no relationship with usury (banking).