I think that as these cults evolve and progress the cult leaders eventually start believing their own BS and drinking their own Kool-aid. They deluded the followers but then they end up deluding themselves as part of the process.
Jim Jones’s son says the opposite—he maintains that his father knew he was a fraud every day of his life, and the psychological torment of that knowledge was one factor that led to the taking of his own life, and taking his 900+ followers with him (1/3 of whom were innocent babies and children; so sad).