Just look what happened in baseball. These are all high profile, highly paid athletes. The players saw the competitive advantage PEDs provided, saw the whole Mark McGuire saga, and determined that they needed to dope to keep up. These were the most highly paid athletes in sports. Alex Rodriguez. Barry Bonds. Heck Brady Anderson hit 50 homeruns. It was almost across the board.
In cycling even after a number of deaths and even after the Festina scandal at the 1998 TDF they doped. Armstrong kept doping even after becoming the patron saint of cancer survivors and even came back to dope in 2008 thumbing his nose at anti-doping authorities. Landis doped in competition. Rasmussen "disappeared" for a few weeks before the Tour to get special preparation. Conrador. Sky. And on and on.
The simple reality is that even the most high profile, highly scrutinized athletes will dope. Even where the sport has things like biological passports. They weigh the risks, realize how much advantage it confers and how hard it is to be caught, recognize that fans will never believe "their hero" is doping, and they do it.