I had an interesting discussion about mental illness with a man I met in Bali. His daughter sees spirits, and talks to them, and leaves out food for them. In a Western culture we would say she has schizophrenia. However in Balinese culture she is considered holy, and everyone in her family supports her. As such while she does have hallucinations, she doesn't have the other negative symptoms of schizophrenia. And her visions/hallucinations have a positive impact in her and other peoples' lives.

I think that biology and culture interplay in complex ways. Someone who is validated by their community and not ostracised and told that they are "wrong" for their unique perceptions, is likely to experience far less trauma and negative symptoms than someone who is stigmatised.

I've heard that the "hearing voices" project has identified a significant number of people with auditory hallucinations where the voices don't say negative things but instead give good life advice. The "evil" aspect of hallucinations tends to come when the person is feeling trapped/traumatised/alone/scared. Perhaps it's like a psychedelic experience, in that set and setting affect whether a hallucinatory experience will be terrifying and destructive, or positive and affirming, or even sacred.

My partner has hallucinations. Sometimes they are dark and scary. But after going through IFS he now sees Pokemon and other colourful, pleasant hallucinations.