That's not actually true. The biggest use is for jewellery. (see https://www.gold.org/about-gold/gold-demand/by-sector) And largely has been for 4000+ years since ancient Egypt.
So, if I were to print bitcoin keys on firewood and sell that, would it become a “good investment” in your mind?
That’s basically what gold is. A commodity with some limited material value, whose price has become completely detached from that value due to its use as a financial instrument.