it is not just the steroids; they are probably even a minor contributor. Wrestling is a rough racket. There is no off season. If you want to make it in the business, you have to be on the road 300 days a year (only the rare few at the very top like Hogan and Dwayne Johnson get to take extended leaves of absence). If you get injured, then your story line falls by the wayside and you have to claw your way back up, so you take painkillers to keep going out there. You take uppers to get up for the match and downers so you can get to sleep. You don't get proper treatment for your injuries because you can't afford to take the time off.
RIP to Helliwig, but man, he was the worst. I mean, he had a great gimmick and was really rolling with the characterization part of the business back in the 80s-early 90s. But he was a terrible wrestler. Worst cardio in the business. He'd come out all jacked up, race around the ring a couple times, jump in and shake the ropes, then have to go into a rest hold 60 seconds into the actual match.