Gold is another store of value, but not that unstable. It reached 2000$ recently and was above 1000$ for many years. Those who invested in gold back in 1900 would have made a great choice since it costed only 20$ back then if I'm not wrong. (Although dollar was way more strong than now)
Bitcoin can lose 500$ within one night. Gold can't. Why that?
Gold has been in use for ages, while Bitcoin came up in the 20th century. And gold is a Fiat currency, its globally accepted as a means of exchange, while most countries don't know what Bitcoin is.