Ultimately, the value of a bitcoin is determined by what people will pay for it. In this way, there’s a similarity to how stocks are priced.
The protocol established by Satoshi Nakamoto dictates that only 21 million bitcoins can ever be mined — almost 19 million have been mined so far — so there is a limited supply, like with gold and other precious metals, but no real intrinsic value. (There are numerous mathematical and economic theories about why Nakamoto chose the number 21 million.) This makes bitcoin different from stocks, which usually have some relationship to a company’s actual or potential earnings.
Without a government or central authority at the helm controlling supply, “value” is totally open to interpretation. This process of “price discovery,” the primary driver of volatility in bitcoin’s price, also invites speculation (don’t mortgage your house to buy bitcoin) and manipulation (hence the well-documented talk of tulips and bubbles).
Bitcoin has made Satoshi Nakamoto a billionaire many times over, at least on paper. It’s minted plenty of millionaires among the technological pioneers, investors and early bitcoin miners. The Winklevoss twins, who parlayed a $65 million Facebook payout into a venture capital fund that made early investments in bitcoin, are now well-known billionaires, according to Fortune.