Gold falls into the category "has always had value, so it will always have value" type of thoughts. And that's just what gives it value, out confidence that we can exchange it for something when you need it.

> A strategic reserve can be ... A commodity, such as intervention stocks of food or petrol ...

> Examples of commodity reserves: Global strategic petroleum reserves ... Gold reserve

Once these factors start to breakdown, all these intangible forms of holding wealth loose value. Gold remains as a significant reliable long term store of value.

Hence it’s worth maintaining by a nation.

Central banks of countries hold various kinds of assets, including bonds and currencies of other countries. But bonds and currencies are just “paper”…or are more vulnerable than gold to shocks in certain conditions.

The disadvantage of physical gold is that it doesn’t generate any income by itself, as compared to bonds.

During times of higher uncertainty, people and institutions (including central banks) flock to gold.