It doesn't even have to be that high of level of competition, just highly competitive. I went to high school in the late 80s/early 90s. Cross country runners at multiple schools in our area were openly blood doping with autologous transfusions. Steroids were openly sold in the weight room and football locker room (and we were just a mid-tier football program). Supplements were constantly coming on the market ahead of regulation; even as a high school athlete I took supplements in good faith that later ended up banned.

We had a very small handful of generational athletes are our school during my time there (at the level where some here would certainly recognize their names). Some were clean at the high school level, some were not. Inevitably the ones who used performance enhancers started having injury issues at the college level that became worse in their post-college careers (olympic/pro). I don't know for certain if the clean athletes stayed clean after high school, but I learned from a couple of them later how hard it was to stay competitive against the wide spread use of PEDs in their various sports.