Gold is the most ductile and malleable of all pure metals (and probably alloys too, since they tend to be harder and more brittle). This is why it's used in computers and advanced electronics, even though silver and copper are more conductive. A very small amount goes a long way, it can still hold together at under 1 micron thickness.

If you tried to hammer lead into a foil that thin at ambient temperature, (which is the traditional way gold foil is made), it would crumble to bits.

Even in antiquity, artisans knew how to make very thin gold foil by hammering it thin, then folding it with paper between the layers to prevent cold welding, and continuing the process, with the number of layers doubling each time.