Gold has been valued across almost all cultures for thousands of years. That creates an expectation that it will still be valued.

And, gold is limited (in recoverable quantities) in Earth's crust. Nobody can print a bunch more of it, unlike fiat currency.

Between those two, it's what many people reach for when they fear that the government is going to devalue their currency. They can buy now, with currency that will soon be worth less, and what they buy will be worth something even after the currency becomes worth less.