A hyperstition is a self-fulfilling belief.
From Give Up Seventy Percent of the Way Through the Hyperstitious Slur Cascade by Scott Alexander:
...A hyperstition is a belief which becomes true if people believe it’s true. For example, “Dogecoin is a great short-term investment and you need to buy it right now!” is true if everyone believes it is true; lots of people will buy Dogecoin and it will go way up. “The bank is collapsing and you need to get your money out right away” is likewise true; if everyone believes it, there will be a run on the bank.