The 80/20 rule applies to everything else. So, why not brain damage? 20% of the "cause" produces 80% of the "effect" and then the law of diminishing returns kicks in. You see the 80/20 rule on talent in guys like Forrest Griffin who are workaholics but, at the end of the day, are just pretty good fighters. Then you get guys like Jon Jones who snorts coke during training camp and is the GOAT. I think that brain damage is mostly genetic. Your brain is either genetically programmed to repair itself after getting hit or it's not. I think that the amount of getting hit matters less than your brain's genetic ability to repair itself. There are guys that have never even had a fight and have just trained in the gym but slur their speech. Then there are guys like Overeem who have been KOd just too many times and seems really smart. Guys like Muhammad Ali who gets Parkinsons and then guys like George Chuvalo who got his jawbone cracked in half by Frazier's left hook, fought Ali multiple times, fought Foreman, fought Jerry Quarry, fought Floyd Patterson, just ate the most brutal shots from the hardest punchers and most dangerous guys in history. Considered to have the best chin in history. Sounds completely lucid at 81 years old. This is just my opinion, which is totally not a medical opinion and based on absolutely no knowledge of anything. What is your opinion?