The idea, your mileage may vary, is that gold's value in, say, hamburgers may fluctuate less than fiat currency. In the strongest gold-bug case, one might argue that a loss of trust in the dollar could make an ounce of gold worth more hamburgers than it could be traded for today.

If preserving value, priced in dollars, is your only goal, holding dollars is guaranteed lossless (modulo tiny costs).