I think they were probably going to die anyway, coincidence and all, some of the time at least. I know so many people who have retired and had amazing lives after retirement.
Retiring at 50 sounds good, I'm past that age myself so...yeah, shite! Lol.
You are probably right, it's likely we are just being fatalistic associating the two with each other. My mother in law, father, and father in law all retired a while ago and are still living good lives these days. As cool as it would be to retire at 50, I just don't think it is practical. I'm definitely going to be looking at a second career if I don't stay on. It might only last five to ten years, but it's probably going to happen.
Good plan, it could re-energize you and some new skills and focus help carry you into retirement more easily. They say a change is as good as a holiday. I know, I just made one myself.