Believers of a less ridiculous conspiracy theory often wrongly claim that a more ridiculous one, like flat Earth, is a psyop or controlled opposition intentionally created by the authorities to undermine and discredit all the other conspiracy theories.
In reality, conspiracy theories like flat-Earth can form due to ignorance, emotion, and prejudice. It is not necessary to invent a conspiracy theory to explain the existence of another. Moreover, all conspiracy theories are more similar than different from each other, including flat-Earth. They differ only in the severity of ignorance, emotion, and prejudice needed for someone to become a victim of a specific conspiracy theory.