It seems that repetitive head injuries are really something that has long term consequences. The issue is VERY complex and has a lot of factors. One thing to look at is the complex data on other sports[0]. It turns out that men's rugby and women's ice hockey are also big magnets, along with soccer/futbol. It seems to be that just about any hit to the head can be damaging, regardless of equipment. The 'violence' of American football may be a correlated factor, but not causative.

But we're just beginning to understand these things. More data is needed, unfortunately. It seems that these athletes really are suffering.

[0] https://completeconcussions.com/2018/12/05/concussion-rates-...

P.S. I've also struggled with these issues. I've written on HN before about them and won't bore here. Suffice to say, though I've had deep struggles with concussions, and in the end I'd say I wish I'd not done those sports as a result, it is a hard question to answer. If I could be back out on that pitch once more with my mates and be guaranteed to not get another head injury, I'd do it in a heartbeat. I loved that time and really do miss it everyday, even decades later, I love rugby. I wasn't an easy thing to quit, and it is still not easy to stay away from. The concussion epidemic is not going to be easy to solve.