According to Osho, humanity imagines ghosts because belief in an immortal soul plus religious loopholes—especially the interval between death and final judgment—require bodiless roamers; primal fear of darkness and danger amplifies it; ancestor-appeasing rituals sustain it; and misread psychological disorders (split personalities) are taken as 'possession,' supplying 'evidence.' Culture, fear, and ignorance co-create ghosts.
We were scared of the dark, didn’t know what happens after death, and when sick people acted oddly we called it ghosts—then rituals and stories kept the idea going.