I think gold is a sure bet, indeed, it is stable. It is therefore very useful to protect its resources from financial crises.
Gold is reliable. But I will not claim that it is a 100% sure bet. Just because during the last financial crisis it performed well, we can't expect gold to remain stable during the next financial crisis. What if some central bank dumps all of its gold in to the market? The prices can go below $1,000 per oz.