Yes, the value is much smaller since your power to keep it is smaller. But the amount will also be smaller. And I would say there are still quite a few situations where having something of trade value is better than having nothing.
I struggle to think of ones where physically-held gold is better than cash. It only happens when your government fails. In that case (e.g. a Communist revolution or civil war) it's easier to kill you and take everything than negotiate. Where it might have had value, e.g. an American holding pounds sterling during the American Revolution, the old money held value. Selling gold to paranoid individuals is so profitable for a reason.
(The only time it may be useful is if you can tell someone about to harm you that you can pay them with something offsite. At that point, however, wired dollars are an easier sell than waiting for a gold shipment that may or may not be accompanied by Marines.)
Fiat currency has become worthless many times in many countries without a total breakdown of civilization to the extent that gold no longer has any value (e.g., Argentina, Yugoslavia, Brazil, Weimar Germany, post-revolution France, ...)