There's no need to be afraid of that ghost up in the attic, those footsteps in the middle of the night, that spook down in the basement, or the bogey-man under the bed. They can't hurt you.
There has never been a recorded event incriminating a ghost or spirit physically harming a person. Most people's fears stem from ourselves, our crazy out of control imaginations and lack of understanding and knowledge of ghosts. From childhood people are taught to fear ghosts, they're bad, relating them to death and evil. So, when that child becomes older and eventually does see a ghost, that childhood curiosity they once had turns, quickly into fear. The fear response, (fight or flight) kicks-in (in this case a taught trait) and the imagination takes over. The person witnessing the sighting of the ghost no longer behaves rationally, he feels vulnerable against something he's been taught to fear, and becomes more accident prone. That's when a person gets hurt. The blame is placed on the ghost.
When a man was asked what happened, after he fell down the basement stairs, his answer was;
"I saw a ghost!"
He might have seen a ghost but he clumsily tripped on the step when his curiosity turned to fear and he tried to run back up the stairs, tripping on the top step. The ghost had nothing to do with him falling, it was the man's attitude (his fear) towards the ghost that made him fall.
That's why people think ghosts hurt people. We've been taught to fear them. Ghosts can't hurt you.