Most of the gold market is “paper” gold, with the physical quantities being stored in a handful of large vaults around the world. The physical retail market is tiny compared to the massive paper market and the hoards of physical gold (owned by nations and large financial institutions) that sit in these vaults. I believe the operators are paid for storage.
Much of the gold in vaults doesn’t even move once it gets there, even through multiple successive owners. China takes physical ownership of its gold, though, so recently there has been a lot of gold moving overseas.
Which is to say, you don't know either. What I'm saying is that this huge boom in gold value has not been matched by an equivalent change in gold storage paradigms. And that... probably has some bad externalities.
We actually saw this in the 1990's. Intel had built its business on the back of regular shipping practices, sending pallets of chips to a small list of electronics manufacturers as needed on commercial vehicles. But as the PC market matured and the parts became more easily liquidated on a global gray market, people suddenly realized that you could hijack a truckload of 486's and dump the multi-million-dollar cargo into Taiwan at almost no risk. And there was a rash of chip pirates for a while.
I am fairly certain that large amounts of gold in transit have extremely high security, as do the major vaults. If you’re talking about theft risk, smaller gold businesses or the couriers that transport for them are probably most at risk as prices rise, as they may not have the scale and resources to deal with sudden changes in the risk environment. But as dollar value increases I’m sure that insurance will require a commensurate increase in security. Basically, robbing banks (or anything similar to a bank) is never a good idea.
It’s not like the quantity of gold available has increased. With China buying and repatriating large amounts of gold, the big secure vaults surely have more space than usual. Some retail gold traders are concerned about issues in the paper gold market, as the total dollars traded is much higher than the total amount in existence, but this concern is just a misunderstanding about how the futures market works. Even so, to me it seems more realistic to worry about some kind of shenanigans in this often opaque “paper gold” market than a sudden outbreak of gold piracy.
Much of the gold in vaults doesn’t even move once it gets there, even through multiple successive owners. China takes physical ownership of its gold, though, so recently there has been a lot of gold moving overseas.
Germany and Italy have recently considered repatriating their physical gold, as they are no longer sure about leaving it in overseas vaults: https://www.ft.com/content/e39390cc-ea02-4197-843a-1e4c24242...