They are totally different assets class.
Gold is the most stable assets class after cash, but it's also the least performance yielding. Hence the idea of gold is to protect against inflation. Buying gold is like have a different kind of cash which sits in the bank. Buying shares or real estates are active assets which you can rent or hold part of a company hence they generate active income.
Gold is great for stability and protection, but it's bad for investments. When you have tonnes of money like a retirement fund or some rich government, gold becomes an important instrument because you cannot dump a few billion in and out of the stock market, not even the dark pool - it will spook everyone.
Bitcoin is in the other spectrum of the assets class which is highly volatile. Yes, it is also a currency which sits there and does nothing, but it's a new unproven currency and with it comes alot of speculation and potential, people are buying into possibilities.
So choosing between gold or bitcoin is a like choosing between caesar salad and a 2kg waygu steak
