The first railway mania (England 1830s). The pricing of the railways was completely insane compared to any reasonable business projections. Everyone was saying

The first railway mania (England 1830s). The pricing of the railways was completely insane compared to any reasonable business projections. Everyone was saying that there was a financial bubble (they were well aware of the Dutch tulip mania) as more railways were built with ever more insane valuations, all designed to be repackaged into shares to be sold onto the next fool. Punchline: because the trains had to stop to pick up coal and water along the way, the railway operators discovered that most of their business wasn't coming from end-to-end journeys between big locations (which was what the railways were built to do), but instead from people getting on and off at stops along the way. With this sudden extra source of income, the railways returned quite a healthy return to their investors.