For decades James Randi offered a million dollars for any evidence of supernatural shit that can be tested. Many people tried, but none were able to produce evidence to earn the money.

If ghosts were a very rare occurrence and only 0.00001% of all dead people produced ghosts we would still be completely overrun by ghosts everywhere, they were would mundane in how common they are. And that’s not counting ghost animals, ghost dinosaurs, etc.

The impulse to believe in ghosts can be explained as well. For most of human evolutionary history we had predators (cats, bears, wolves, hyenas, etc). If you heard a noise in the bush and didn’t assume it came from an agent you were more likely to be ambushed than if you assumed it was an agent even when it was just the wind. The survival trait biased us towards assuming agency even when it’s not. When you hear a noise in your home at night your first though isn’t settling foundations, it’s intruder.