Why did Harry Houdini investigate and expose some mediums?

Harry Houdini, a renowned magician and escape artist, investigated and exposed various mediums because he believed they were charlatans who exploited the public for profit.12

Houdini argued that the phenomena presented by these individuals—such as levitation, slate writing, and spirit photography—were not supernatural but were instead produced through natural means, mechanical ingenuity, and clever tricks. He viewed these practices as fraudulent, particularly as interest in psychic phenomena surged following the mortality of World War I, creating a lucrative environment for deception.12

Throughout his later years, Houdini dedicated himself to unmasking these performers, documenting his findings in works such as A Magician Among the Spirits (1924). His commitment to exposing such fraud was rooted in a firm ethical stance against the deception of vulnerable people, and he frequently demonstrated that the effects claimed by mediums could be replicated by a skilled conjurer using natural methods.12