Tulip Mania
In 1630s Holland, a single tulip bulb of the right variety reportedly traded for the equivalent of a skilled craftsman's annual wages. A futures market sprang up around flowers that had not yet been dug from the ground, prices climbed in a self-reinforcing spiral, and then in February 1637 the whole thing broke. Tulip mania became the textbook bubble, even as historians still argue over how severe it really was.
For founders, operators, and anyone allocating capital, the value here is the pattern, not the flowers. This case sharpens the judgment of spotting when a price or valuation in your own market has detached from any coherent story about underlying worth, and the main reason to buy is simply that everyone else is. The feedback loop that drives a mania is easy to describe and brutally easy to get caught inside. The specific warning sign that tells you you're already in one is the payoff the app withholds.