Oh, well. The Markses are a Florida family of “psychics” – or “ex-psychics”, perhaps – who claimed their powers could influence terminal cancer and allow them to peer into their victims’ previous lifetimes, which, of course, they couldn’t. The business, which seems to have been masterminded in particular by Nancy Marks and her mother-in-law Rose, would choose their victims carefully, targeting those who had recently suffered devastating losses, to milk them for huge amounts of money, and several of them accordingly received substantial prison sentences back in 2012 and 2013 for defrauding clients of hundreds of thousands of dollars.
Now, one might easily suspect that the Markses weren’t exactly acting in good faith, and do as such not deserve and entry in an Encyclopedia of loons (hence the question mark), but Nancy Marks’s defense did argue that she “didn’t know what she was doing was wrong,” and if that is true, it’s good enough to qualify as a loon even if you don’t really think you’ve got psychic powers.
Diagnosis: It is, however, not easy to distinguish what the Markses were doing from what “ordinary” psychics are doing. Hopefully they’re neutralized, at least.