Yeah, keeping people alive seems a good reason! Unfortunately it seems it doesn't always work.
There are numerous surveys of track and field athletes that lead to some quite alarming conclusions. In one, something like half or more of those surveyed said they would take a substance that was:
A. Undetectable
B. Would guarantee a (Olympic) gold medal
C. Would (significantly) shorten their life expectancy
I don't think for one second that track and field athletes are any different to those in other sports. Indeed the financial rewards are far greater and the lack of effective testing more obvious outside of athletics.
Another anonymous survey, again reproduced on more than one occasion, suggests that between 25% and 45% of athletes will admit to illegal doping. I suspect there is some reluctance to admit even in an anonymous survey, so these numbers probably understate the prevalence.
It would seem that individuals are making, or having to make, the choices in any case. That does change the nature of sport from one of competition on the field to one of risk acceptance and genetic response to doping approaches. It doesn't necessarily harm the spectacle of course.