"Many think that the short term gain will be worth the long term gain, but it isn't. In addition, using steroids is cheating, and there is nothing worse in sports than a cheater. Don't do it." 

This statement is telling us to not cheat. Don't do drugs at all. And also using steroids is cheating because it extends the performance of the athlete than what is capable of doing. When you cheat you don't have the same feeling as when you win from your own capability. For example you cheat on a test and you score a perfect score you don't feel the same way as if you were going to do achieve from not cheating. Or if you cheat on a mile test. You skip a lap and say you did it. It's not the same as doing it all. Or is you use steroids when you are going to play a game. And you do it others may not catch you. But you know that you did it and you will feel guilty yourself.