Let's set aside the obvious, that it probably has a lot of downsides and doesn't work well (like shrinking testicles and heart problems from steroids).
Our society has a real discomfort with "improving" "healthy" people. We make a clear, but somewhat artificial distinction between healthy and diseased, and the diseased people can get recognition and treatment but the healthy ones cannot. That's why there is often a battle to have certain things recognized as a medical condition. For example if you have trouble focussing, you might be considered lazy, but if you get a ADHD diagnosis people will be more accomodating (and you can legally take amphetamins!).
I was never especially athletic. I would love to workout more, but find it really hard to make time for it between work and family. And found that many people in my social circle or at the gym don't encourage me but make me feel like I don't belong there. But if I had a "real" recognized medical condition that required physiotherapy, I would get time off work and would get the gym paid (in my country), and most important people would support me. But if you are "healthy enough" and just want to improve yourself, you are on your own.
I would love to have a world where everybody can strive to improve themselves - become more healthy, strong, beautiful, smart, and so on - and where you would get the resources and the support needed to do so.