You don't just want the best investment, you want several good investments that are uncorrelated with each other. Gold is better if you're looking for something

You don't just want the best investment, you want several good investments that are uncorrelated with each other. Gold is better if you're looking for something to diversify your investments in the stock market, since it tends to do well when stocks are doing badly (though that's not guaranteed). Bitcoin of course has been better for really high returns, mostly when stocks are doing well. Whether that will continue is anyone's guess. Long-term returns for gold have basically matched the S&P500 total performance since the bottom of the dotcom crash.