Did you watch the movie Concussion ?
Discussion
Physical injuries are relatively low in American football. Brain injuries/diseases are very frequent, however. It’s like smoking… you won’t die after a single cigarette but it’s repeated exposure that is very damaging.
Great Freakonomics episode worth a listen:
https://freakonomics.com/podcast/how-much-brain-damage-do-i-have/
Also, “87% of players show signs of brain injury”. So “injuries are relatively low” is definitely not accurate.
https://jamanetwork.com/journals/jama/article-abstract/2645104