In an interview with the UK Sun, Jim Cornette talked extensively about wrestler deaths.  Of note:

It is never easy when a friend dies.  But at first it was 'oh my gosh', then it was 'oh no', then it was 'not again' and finally you're not surprised anymore. It is never good, but it isn't shocking. That's the sad thing.  It is more shocking if a professional wrestler from the 1980s is actually found in good health and living a nice life with no problems.  When I was a kid watching wrestling in the 1970s, every couple of years you would hear of a few wrestlers dying in a car wreck.  Now a month doesn't go by that you don't hear some about wrestler dying at an early age, because of drugs or by-products of drugs which are by-products of the unfortunate work environment that they found themselves in.

There's a lot more in the article about the possible causes, which is more of the usual, including Cornette's thoughts on how stylistic changes made painkiller problems worse.