Listen, not to be callous, because nobody, especially stand-up guys (by all accounts) like these guys should lead lives this short, but you can't go around pointing fingers at sports like hockey and football and say that's why people do horrific things to themselves. Yes, there is evidence that some of the hits these guys take fuck them up later in life. But also, violent sports, by and large, attract people that are a little bit crazy, guys that "do" first and "think" second. Personalities that live life hard and take things to extremes. It's the same profile of someone who abuses their body until they die.
In short, we love to watch these guys on the ice and the field because they are crazy, and sometimes crazy people do crazy things. So while it's very easy and apparently in vogue to blame the sports for its participants' actions, I think you really need to look at the people who choose to participate in those sports, and see the larger pattern for what happens to them as their lives proceed. Just my two cents. I could be wrong, but I doubt it.