I mean, you’ll find people using PEDs in any sport, despite the risk of bans and everything. Steroid use is also rampant among bodybuilders.
There is an “obvious market”, but why do such sport leagues or federations that openly allow those drugs exist?
I can imagine that such a thing existing would create an immediate and widespread health problem with lots of people, athletes or not, using those performance enhancers and accidentally fucking themselves. But what else could be a problem?
A lot of the drugs used generally requires a prescription and is only available legally for therapeutic purposes.
Most of the testing done by sports leagues is done because they would rather handle the issue internally than get the government involved. Even then, a lot of the internal regulations are usually only done to get the public off the leagues’ back.