Let me explain- the real reason we have psychosis is because part of the brain called the anterior cingulate is broken. Normally, the anterior cingulate keeps emotions from domineering thoughts. It checks the emotions at the door before they reach into the conscious mind.
It is broken, and our emotions spill into our conscious cortices as hallucinations and delusions.
This means that the symptoms are actually unconscious phenomena which have slipped into consciousness with no checks and balances, and thus they seem real.