Psychics/mediums are doing harm. They may wrap up their lies and fraud in a false justification of helping people, but to believers their words are so strong, to them its real. And all it takes is one wrong word from a psychic, and you are left with an eternity of hurt and regret.
Here is a news story from KMOV on just such a victim.
KMOV's hidden cameras capture self-proclaimed psychic Sylvia Browne making bold predictions about a mother's dying son. Not one of Browne's predictions came true. The woman's son died two days later. This story was on KMOV-TV in May 2010.