Fantasizing in your own mind is still different from actually talking with a real LLM. I think the poor responses from an LLM can easily shatter the illusions in your mind.
It's true about poor responses from people too. (Had delusional crushes on real people too.) An LLM has the advantage that it doesn't have a self to feel unmirrored (can mirror you wherever you goes) and never feels squick so it has the superpower of following you into every fantasy.
In conversation I can never tell it apart from a real human.