I think it's been covered, but some professions are just dangerous, period. Soldiers, firemen, football players, boxers, coal miners. Heck, my dad got an asbestos settlement. Some jobs come with hazards.
Having said that, I think in some ways the potential harm from football is exaggerated. I'd argue that on the amateur level, at least if you are speaking of high school football, the benefits outweigh the risks. Is it really safer to spend those years in front of a computer eating Fritos? They say sitting is as bad as smoking. There are still a lot of things to be learned, but from what I've seen, it is doing things in excess that tend to create these dire consequences.
There's a massive difference between a few years of football, and playing football for decades. Furthermore, the difference grows once you reach a professional level, and there are bigger, stronger people hitting you. The severe problems we are seeing tend to come with a lengthy career in football. There's plenty of people that played high school football and college football that are not impaired. I think we can all agree that becoming a professional can push the body past its limits and that's a choice some people make.
There's also a common sense aspect to this. There are plenty of sayings about "getting hit in the head too many times" or "getting dropped on the head", we know getting hit in the head does damage. That's just common sense. We've all had it though pretty much, anyone who is active has had blows to the head. The key question here is just how many a human being should sustain and how to avoid that. I'd add one last thing. It's still not an excuse for certain behaviors. It's an impairment, but some people are born impaired. It's not an excuse for things like OJ did, or any number of violent people. It's a problem, more research will be done, but ultimately actions have consequences.