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?
For me, it's because Bitcoin has a finite supply of just 21 million compare to our local currency that has unlimited supply. Plus, no central authority are taking control of this cryptocurrency because it is operating under a decentralized technology in the form of blockchain.
These are some of the factors regarding Bitcoin's unstable price. Anyone, even a kid, can own Bitcoin rather than the traditional stocks which are centralized and limits only to the accredited investors. As we fully control our own decisions, that's where volatility is high depend if it goes high or low.
We all aware that bitcoin are completed controlled by our own decision and sometime we also can make a lot of mistake that might losing our own money because of a lot factor like getting scam or losing or private key. Its was a high risk rather then gold that has it own physical values and can be stored in the bank in case we want it to be saved and can be insurance if it get rob.