The reason we have to stand up against performance-enhancing drugs is not because it's cheating. It's not to protect the people who bet on sports. The idea of protecting gamblers over competitors is heinous; it's the Hunger Games.
The reason we have to stop performance-enhancing drugs is that if any athletes do it then they all have to do it (or they might as well stay home). It's not fair to athletes to force them to take drugs, shoot up their own blood, or do anything else that could harm their health.
In the old days we saw elite athletes on steroids die of heart attacks in their twenties. We don't know what harm the current drugs do. Could they have caused Lance Armstrong's testicular cancer? There's a chance they did.
I don't blame Lance Armstrong for cheating. As the US Anti-Doping Agency found, it was "not possible to compete at the highest level without them" during the time he was competing. Lance Armstrong is not the problem, the system is. If we react to each scandal by blaming the athlete, we won't stop the scourge that's endangering our young athletes.