Not sure on mental illness since I'm not a psychologist or psychiatrist, but in my opinion, it appears that Lett and Morris in particular have personality disorders (ie: narcissism, sociopathy... basically under the antisocial personality disorders category).
i have met and spent time with lett personally. Don't let the wackiness fool you. This man was the most self-centered, domineering person I've ever had the misfortune of being around. His mere presence commands reverence (at least that's how he presents himself). He is actually very intimidating and seemed to jump on every opportunity to call people out publicly (in relaxed social settings--these were not theocratic settings but I cannot go into too much detail. PM for info). He mastered the art of gaslighting and manipulation of people to get his way via passive aggression. I felt as if I was in the presence of Bond villain-level evil; genius evil, that had been tested, refined and sharpened to perfection over decades of experience.
Morris, on the other hand, appears far more sinister. He's relatively new to the "truth" compared to many of us, even. From what I've learned about him, he was successful in the secular sense as well. He joins the bOrg, rapidly accelerates rank while raising a family and became a circuit overseer in no time (most of whom cannot reach that level without some financial security, the ability to hob-nob, and a ruthless spirit to pursue and obtain power). His accension to the GB was super fast and really kind of sketchy if you read his recent article. How did he do all that he did? I know FAR more "qualified" men who have struggled for decades to become a mere circuit overseer. How did Morris get thru so fast only to be tapped for GB within a few years after that? In my opinion, it's his dominating and fearsome personality. Carnegie, Rockefeller, even that bitch who resigned from Reddit recently all seem to have that same ruthless "mojo." They climb because they push and shove others out of the way. Bully elders at local congregations compare at a smaller level. I'd often wondered when every KH had "that one elder with the Napoleon complex who everyone hates" how they GOT that power and how they KEPT that power. These sociopathic people exude an extra perception that entire groups of people can be manipulated by. Morris is a prime example of this and now, he has a TV station and can infect every family home and local KH with his hypnotic control. He's dangerous. He's wicked and he's a cold, calculating motherfucker with absolutely zero empathy.
both Morris and lett do not care about others at all, in my opinion. They've achieved their position & rank even under questionable circumstances (partaking at a time in JW lore when it was highly suspect for anyone born after 1935 to do so). People looked down and said nothing. Their crazy mannerisms and personalities are also observed by even the most loyal JWs, but people look down and say nothing. It's that PERCEPTION of power by their calculating manipulations and dominating prowess that got them where they are and will allow them to continue. Unfortunately, they also appear very healthy. There is such a thing as bad people being too mean to die. They'll live for a very long time and will continue doing more damage and harm to the lives of millions worldwide because sociopaths & evil people like them always do. I wish they'd get leukemia or something, but it's just not gonna happen.