"None of those supposed mediums are legit"...............and you
know this to be a fact or "believe it" to be a fact?
By the way "cold reading" does not explain something that was said between two people that no one ever knew was said, and I mean "specific" words and events that happened.
I do not for one second doubt that the large portion of Mediums are scams. Nonetheless, in history there have been many mediums that stated or predicted something before the fact that were never paid to say, had no personal benefit in saying them, or that had any clues that would help them say it.
Evidently, you have not done much research on the topic. I have done a fair amount and am presently expanding my research on it.
Start here: