Actually this is a relatively new phenom happening. If you go back to the old school wrestlers, they are still alive and kicking. Superfly, Hogan, Sammartino, etc...
Hell if anyone should be dead, it is Ric Flair. That man simply could party all night and then show up the next day and put on a match of his life. When he was in WCW, I would see him and a lot more WCW wrestlers at Chicagos Pizza in Atlanta on the nights the WWF had their pay per views. I swear to God Flair would drink at least 30 kamikazes in the 2 hours that pay per view was on. Plane crash, broken back, etc.. dude survived it all.
It is the younger stars that can't keep themselves together.
Luger - living in a friend's basement and looks like shit.
The Steiner bros - multi injuries/surgeries and still look like shit
Sting - dude is wearing a padded body suit at times, looks like shit
and these are just the stars still alive.