i don't think it's CTE. i think the majority of guys who do insane shit were already crazy. Diego was already crazy. BJ was already crazy. Jon Jones was already crazy. you don't see any of the Pride guys acting like maniacs and they're older and arguably have endured much more punishment than these UFC guys, same with the old K-1 guys. Mike Bernardo probably had CTE but he didn't do any crazy shit that endangered others, sadly he committed suicide.
i don't think it's necessarily MMA turning them into this. i think it's crazy violent people who were attracted to MMA in the first place and then got older and aged and incurred more damage but the insanity of them is on them, not on the brain damage. that just allowed the mask to slip more easily in my opinion.