The thing I find interesting is PED use actual levels the playing field some what. Remove PEDs from the mix and genetics determines ultimate potential.
There is nothing inherently fair in sports. With respect to distance running, Grow up at altitude, you got an advantage. Have a light frame, advantage. Good natural biomechanics (advantage). Resilient body that doesn't get injured, advantage. I could go on.
Yes, many of these things can be improved with training. Mental toughness certainly plays a role.
Folks want to believe that working hard and grit will win you an olympic medal. Nice thought but that doesn't make it true.