Arsenic, the more I've read your posts on this forum, the more I've become convinced that you are either (a) Purely a troll, or (b) Always trying to play devil's advocate.
In Benoit's case, the leading cause has pretty much ALWAYS been the repeated brain damage throughout his career which led to CTE.
To quote:
Tests were conducted on Benoit's brain by Julian Bailes, the head of neurosurgery at West Virginia University, and results showed that "Benoit's brain was so severely damaged it resembled the brain of an 85-year-old Alzheimer's patient." Tests conducted on Benoit's brain tissue revealed he did in fact suffer from severe chronic traumatic encephalopathy (CTE), and had brain damage in all four lobes of the brain and brain stem. Bailes and his colleagues concluded that repeated concussions can lead to dementia, which can contribute to severe behavioral problems. Benoit's father suggests that brain damage may have been the leading cause of the double murder-suicide.
Steroid use could have also been a factor, sure, but he hadn't been using artificial steroids which athletes use. The only artificial steroid found in his toxicology report was the testosterone cypionate that is prescribed for RECOVERING, FORMER users of steroids as testosterone therapy. The amount in his blood was also at a normal level as to have been a testosterone replacement.
The main issue was his brain, though. It was severely, severely damaged, and I don't think you understand how much that can change somebody (I'm going to assume you don't have any academic history in cognitive neuroscience like I do, or maybe no background in biology at all).