A lot of them don't die young. Look at Arnold, he's practically elderly now. A lot of the old greats who obviously used are all old men now as well. Ronnie Coleman isn't young anymore either.
I know a few people who are 'on' almost year round - they have to be to maintain that kind of size. But it doesn't necessarily mean you have to be unhealthy. It sounds unlikely, but it's true. One guy I know only comes off for about two months a year. He gets constant bloodwork done, however, and keeps everything in line. He's even managed to concieve two children since he began doing this sort of thing.
Of course these guys I'm referring to never use orals, so that could be a part of why they aren't all screwed up.