He was the one largely responsible for a lot of that thought. He wasn't just doping himself, but set up a whole system for cheating throughout the sport. So ultimately, he damaged the sport in a much more significant way than just doping himself. that's not really true. one entire team (festina) was caught cheating in 1998 before armstrong even came back to cycling, and a number of other finishers were very likely doping (the top four finishers were either accused of doping or caught doping later in the their careers). armstrong certainly didn't help matters, but it's more accurate to say that he continued and probably expanded on something that was already rampant throughout the sport.