***or runaway inflation/devaluation of a nations currency,***
Gold used to be worth $19 dollars to the oz. One oz of gold could be cut into 19 pieces and each called a dollar. Then it was $23, then $32, then $35.
Today GOLD is $1500 paper dollars to the oz. That means that if gold were used today, each oz would be cut into 1500 pieces and is called a dollar.
Which means, each dollar is worth less (worthless).
And if the US Government collapses, it will be worth the same as confederate money in 1866.
That stuff's worth more today! I have a decent collection of confederate currency. Of course, it's collectible value, but still pretty neat!