Smart people believe weird things because they are skilled at defending beliefs they arrived at for nonsmart reasons. —Michael Shermer (Scientific American Sept. 2002)

When you believe something you generally prefer facts that confirm the belief, and you ignore or rationalize anything that contradicts the belief. The smarter you are, the better you are at rationalizing whatever you want to believe.

A cartoon shows a doctor speaking across his desk to a patient.

Orthodox medicine has no known cure for your condition. Fortunately for you, I'm a quack.
—narrated by Martin Gardner

These confidence tricksters emotionally control and psychologically manipulate clients by tapping into their vulnerability and fears.

The manipulation concludes with the client accepting the practitioner's personal judgments and biases about the client's lifestyle. This can take the form of telling people what they should throw out or save (as if a complete stranger would know!), and (as in the previous example) who they should throw out or keep around. The emotional control and manipulation carefully prepares a client for the final indignity of the confirmation bias.