Passed through this many times, but the matter can become somewhat evasive, as it can get lost in the muddle of a bunch of long words that can make little sense if a strong command on the field isn't there.
There is a book that had a copyright back in the late 1940s, by The Philosophical Library, Inc in NY, NY.
It defines dereistic thinking. Reference, 'disregard of logic, reality testing...', and perhaps pertinent in today's times and some of its societal challenges, '...according to Bleuler, it is the type of thinking which is found in daydreams,... and paranoid schizophrenia, the motivation coming from the innermost nature of the person'.
Whether I agree, totally or partially, about the aspect of 'coming from the innermostnature of the person', or not, is another discussion, as the innermost is likely created in a way that is healthy, in for instance the original.
What might be up for discussion, is it is pointed to that schizophrenic like behaviors might, be ones that can start to become further and further ingrained or sunk deeper into the psyche, mind, etc., of individuals, if the individuals are not on track toward regaining or becoming healthy as far as their conditions.
Look at [the word] 'motivation' in the book's definition-, then apply to pracical usage, such as the motivation or motive of an individual, wher sole or group, commiting a horrific crime.
The loophole: The same book describes fantasy, and says 'daydream; or autistic or deisristic thinking', that's the verbatim SPELLING of the original 40's book I have. The problem is apparent, deisristic is highly likely to be a misspelling of dereistic, the letters probably got jumbled in the type up or publishing. [If you look up 'deisristic' online, unless there is a suggested correction/ autocorrect, you probably won't find anything, because there probably isn't much out there to find, no such word for the practical most part exists.]
So if your reading stops at the entry for fantasy, or skim through it once starting with entries after e, unless you know dereistic is what's supposed to be there, basically the entry has elements of nonsense that might lead to nowhere.
Recap of the loophole closed, and breaking it down into smaller elements:
The Philosophical Library's information (spelling revised; font colors used to match key words up):
'dereistic thinking' defined = type of thinking which is found in daydreams,... and paranoid schizophrenia;
'fantasy' defined = daydream; or autistic or
deisristicdereistic thinking
Dereistic thinking defined from
https://encyclopedia.arabpsychology.com/dereistic-thinking/#google_vignette
"Dereistic thinking is a cognitive bias that occurs when individuals fail to consider the context or facts of a situation and instead rely on their own assumptions and beliefs. This type of thinking can lead to flawed decisions and can be especially dangerous if the individual is in a position of authority."
More on dereistic and dereism definitions:
dereism
noun
de·re·ism ˈdē-rē-ˌiz-əm ˈdā-rā-; dē-ˈrē-iz-əm dā-ˈrā-
: thinking directed away from reality and not following ordinary rules of logic
dereistic
ˌdē-(ˌ)rē-ˈis-tik
ˌdā-(ˌ)rā-
adjective
dereistically
-ti-k(ə-)lē
adverb
The root of dereistic, dereism and other forms:
Etymology
From Latin de re (“away from the thing”) + -istic.
Adjective
dereistic (comparative more dereistic, superlative most dereistic)
(psychiatry, dated) Not in accordance with reality.