I truly think that when they started, back with CT Russel they were sincerely searching for something different then what was being offered by conventional religion. That being said they had it wrong, time has proven that, but that didn't stop them instead they changed their doctrine as needed to fit the current obvious evidence.
Time proved them as false prophets, but up to that point they amassed a large following and wealth, there doctrine is to blame for much suffering and death. Abstaining from blood, Rwandan military cards and Nazi concentration deaths just to name a few. How do you come clean now? way to much liability, to much guilt and shame instead continue the sham and hope there might be some truth to "a end". I think they honestly believe in a God who will bring an end to this system regardless if their doctrine is right or wrong. They are banking on this.
"Religion is the sigh of the oppressed creature, the heart of a heartless world, and the soul of soulless conditions. It is the opium of the people" Their will always be a need for religion.