No, I never said anything like 'Unhelmeted cyclists are invincible'. I specifically said that luck plays a large part in sustaining head injuries. In your case, in all likelihood, your helmet made no difference whatsoever and you would have been injured with or without it. And we know this because even helmet manufacturers state that their bicycle helmets are not designed to prevent the sort of injury you received.
As an aside, for the folks here who are suffering from confirmation bias, your story is precisely an example of that phenomenon. You want to believe that it was your foresight and intelligence in wearing a helmet that day which saved your life. I get that -- everyone wants to believe that they are in control, and no one wants to believe that they just got lucky. So everyone wants to believe that, as long as they wear their dainty little plastic hat, they will be safe. And I get that too, feeling safe is nice. But feeling safe is not being safe, and it is important to recognize the difference.
To the point, an equally-valid interpretation of your story is that your helmet did a very poor job of protecting your brain, and you wound up in a coma despite wearing your hat.
It wasn't my foresight and intelligence. I bought that early Bell simply because I'd ridden a first season of club racing wearing the required leather hairnet. (Peloton joke i heard many times - we wore those so we could have open casket funerals.) Vowed to myself if I raced another season, I'd by that goofy Bell. Next March, I decided to race and bought it, wearing always so I'd be totally used to it come July and the high 90sF. That November I was wearing it simply because it was like putting on my shorts.
That crash was from my fork breaking at the crown, no warning at close to 30 mph coming off a routine bunny hop. I never got my hands off the bars. I'm no gymnast. It was a head hit, then shoulder.
"In your case, in all likelihood, your helmet made no difference whatsoever and you would have been injured with or without it." Umm, yes. Injured to the life of a vegetable or dead without it. Unless you are much smarter than the best at Massachusetts General Hospital's ICU where they had one of the early CAT scanners. The hit was a couple of inches above the corner of my eye. Broken skull there just might be traumatic, maybe? True, I probably don't have the thick skull you do.
Edit: The CAT scan showed just a small blood clot on my hypothalamus and a bruise on the base of my motor nerves. 5 days later, next scan showed those healing well. The consequences to me were the big deceleration my brain took (and rebound as that was the early firm polystyrene(?) foam). Skull was fully intact. That hit was exactly what those helmets were designed to deal with. I lived and I'm here. I would challenge you to do the same crash without helmet and report back but my faith won't allow me.