Does a CEO of a fortune 500 company believe in their corporation? I think it's pretty much the same with the Gobbering Body of the JW religion. They force themselves to throw aside doubts and nagging thoughts from their minds that what they're preaching, what they're selling, is no better and sometimes worse than other competing organizations.
I think Rutherford was a megalomaniac, and a psychopathic narcissist, but I doubt the current GB would consider braking away from Rutherford's wacky doctrines. It would be nice if they could see the error and cultishness that is rampant in their religion, sort of what took place with the Worldwide Church of God (Armstrong). It takes integrity and conscience to make changes like that.