Believe a bank is about to fail, and your belief alone can help make it fail

A self-fulfilling prophecy is a prediction that comes true largely because people act as though it's already true. Sociologist Robert K. Merton coined the term in 1948, using the example of a rumor that a perfectly solvent bank is about to collapse: depositors rush to withdraw their money just in case, and the resulting run actually bankrupts it. Merton argued the same mechanic drives stereotypes that provoke the behavior they predict and panics that cause the very crash everyone feared.

— Robert K. Merton, The Self-Fulfilling Prophecy — The Antioch Review, 1948