Hilariously, this is itself a conspiracy theory.
https://en.wikipedia.org/wiki/Conspiracy_theory#Etymology_an...
> The term "conspiracy theory" is itself the subject of a conspiracy theory, which claims the term was popularized by the CIA in order to discredit conspiratorial believers, particularly critics of the Warren Commission, by making them a target of ridicule.
> The earliest known usage was by the American author Charles Astor Bristed, in a letter to the editor published in The New York Times on January 11, 1863. He used it to refer to claims that British aristocrats were intentionally weakening the United States during the American Civil War in order to advance their financial interests.