A guy who is really into the psychology behind "magic" once explained how he could accurately predict the future of several people. There are things that are very likely to happen to you anyway, and things people love to hear about themselves, and mixing these "always true" things with what people wish to hear you can easily come up with a story that would satisfy anyone. Sometimes they can ask you a few questions that may appear completely irrelevant, but to which the answer can betray a few things about you, and all that is taken up in the prediction story. So fortune tellers in carnivals should mostly not be trusted.
I did once however hear a story about a murder investigation in which the cops were completely stuck. They had a suspect but no evidence and even they knew that the suspect could very likely be innocent as well. Just in a matter of desperation a medium came to the scene of the crime. All she wanted to know was the exact spot where the body was found and to have a personal possession of the victim, from there she said things that made a fitting story in which the suspect they had was immediately in sight as the culprit. Now the story of a medium has no value in court, however her story brought the cops to new insights to find the evidence that would be irrefutable in court, causing the suspect to be tried and condemned to death after being found guilty. (Particularly because death row was the punishment, the leader of the investigation wanted to be careful with what a medium had to say, but the leads she brought in were so solid, he could not ignore it, and when the evidence was found, it was so solid he is sure he got the culprit and the culprit's confession even fit the medium's story, while the culprit never knew a medium was involved in the investigation prior to his confession).
A lot of things happened that make me believe there are things science can never explain and which may seem supernatural or unreal. People really bringing that with a crystal ball and making money out of it or run a TV show about this...
Oh course, I have many many predictions myself which became reality. How could I do that? By logic thinking and knowing a few things about history. Sometimes supernatural powers are not needed to predict the future or to know things without having been on the place where it happened at the time it did.