This is the argument I dont get. Comparing what happens in a football game with fully padded men to drunk driving or any other crime is an extention of the wussification of society. In my view, football is an outlet - a relatively safe outlet.
Also, the reason that the NFL career is 3.3 years has to do with new players coming in...and after 3.3 years they can use their college education for another job - there should be no guarantee that once you are out of school you stay in that profession for life - especially football players.
You missed the point....yes, not a comparable example, but, the point remains. What was typical 20 years ago whether in a given sport or outside of that is perhaps not so typical or completely different today. My point, a rather simple one is that norms change.
There should be no argument, however, that with the increase in size and speed, the pressure to keep players in the game (money) the game is more dangerous. Impact is greater and injury more prevalent despite improvements in equipment. In fact, some suggest improvments in equipment have created more injuries (for complex reasons) So, as far as your suggestion that injury is not part of why the careers are so short is not supported by people in the field, particularly the NFL Players Association.