Yeah, but by the time you are 70/80 it won't be the crap your pants, not recognizing your family years. My father is 75 and he is pretty active and has no more dementia than he had when he was 40 (granted he has been insane my whole life so it is hard to tell). The 40 something generation will likely have active lives into their 80s and 90s.
And the thing is with all these violent hits the NFL players take, most of them don't avoid the crap your pants, not recognize your family years. Those years just come to them in their 40s and 50s, sometimes 30s. Ask guys like Kevin Turner and Wayne Chrebet if they would trade the football life for an extra 10-15 years of life.
I remember seeing Steve Young down in N'Orleans for the first Belichick/Brady Super Bowl and he was walking like a 90 year old man. I can only imagine what he looks like and what he is going through 15 years later.
The trade off for most NFL players isn't usually that they avoid having their bodies break down before they die, but they die younger. They die younger because their bodies break down sooner than the average person and they usually deal with a lot of medical issues the average person experiences in their senior years in their middle aged years.
There are no guarantees in life. Just because you choose to take the safe path does not mean that you are going to live a happy and healthy life into your nineties. The reality is that many of these people in their eighties and over don't have a lifestyle that anyone envies. I've seen it happen to my parents and it comes on quicker then you ever would think. There is also no assurances that people even younger won't come down with a wide assortment of medical issues from cancer, to heart attacks to diabetes and more.
I would never put of something I love to do just for the CHANCE that I MIGHT be healthier 40 to 50 years from now. There is just too much variability between now and then.