It's also useful in the arts, electronics, lubricant for spacecraft, and as a money that survives civilizational collapse. Gold has been demonetized many times throughout history but that has yet to stick.
Discussion
Sorry, I made a mistake. Arguing over whether something “is” something is generally unprofitable. It’s a trap I usually avoid, but have fallen headlong into it here. 🤦♀️
I hereby concede that gold “is” money.
Further, I’ll make a prediction: neither gold, nor gold-based credit, will ever again achieve broad usage as settlement for exchange. To put a number on it, I predict that less than 1% by count and 5% by value of exchange settlement worldwide will be in gold (or gold IOUs), forever.