that level of denial is likely related to a personality disorder
personality disorders are never cured, only managed and that takes constant work and sometimes medication
my lived experience is that people with personality disorders know what they are doing and don't care to change
unless of course their behavior leads to them not getting what they want - in which case they change for a bit to draw people back in, only to abuse them again
that is a conscious choice
@samiamsam I'm a licensed MH professional: tons of folks without personality disorders go into full clinical level denial about lots of things.
People in substance abuse recovery (for example) do not do sociopathic things like steal from family members once they are in recovery.
Clinical denial is tricky as hell and -not- well understood by most of us- and it has been present in lots of people in every human caused atrocity that has ever happened.
Psychology has tons of work to do.
I saw that film when it was first shown - it was utterly chilling.