I really don't think you get it. I care what happens to my favorites regarding their career. If GSP got hurt right now, I'd think "damn... his career is over.. that's such a waste"
the lesnar example you used earlier is interesting because... well his career is over, he's never going to fight again.
Now I'm not inhuman. I don't want anyone to die in a car accident, not even you (well... maybe, na j/k) but now that he's retired, he's just a person. Finding out he died, finding out michael jordan died, finding out Ali died (or anyone else who's days of entertaining me are over)
would simply get a "ahhh.. that's too bad" out of me, and then I'd move on within seconds.
Why? Because I don't know the man. My relationship to him is only as a fan of his fighting, now he's not fighting, so now I have no relationship to him (other than a little nostalgia)
It might be a little different with movie actors cause they could always come back to do one more role but athletes? once their career is over so is my concern (beyond the most basic human respect that I'd give anyone-- literally brock will get the same "ahh too bad" as "random lady #5235")