I have argued for years that "reality-testing," which is the measure of psychosis from any cause, is a spectrum and not binary. Reality-testing has many grey areas. I have even argued that imperfect reality-testing in some areas is a normal part of human mental life.
Most areas of mental life are far too complex to be reduced to black-and-white distinctions. I am pleased to see that others are talking about it. For example, Viewing Psychosis as a Spectrum.
I believe in Santa. Don't you?