Interesting to see them mention tulpas here. It's always been a bit of a meme online, but I knew a pretty tenured hypnotist who was utterly terrified of the things. He'd seen tulpas cause irreversible psychological damage to the people who adopted them, where many people would become completely attached to a character or particular fiction in their head. This could cause them to act out involuntarily, induce constant…
What's interesting about this stuff is that it seems to support interpretation through multiple cognitive frameworks. There could be a mystical/esoteric explanation for why those people became so attached to the characters or fictions. Or it could be that they were already vulnerable to schizophrenic or depersonalization/derealization-type disorders.
It's like how you'll sometimes hear/read people say that tantra/mediation stuff like Kundalini can be dangerous because it results in an energy imbalance that could potentially be irreparable and/or lead to lasting damage.