If steroids win fights, how would a juicer ever lose? If steroids were a clear path to victory, everybody would be on gear and every fight would be a draw. Your logic is seriously flawed. There's so much more to fighting than just the things steroids help you with.
If one fighter is a juicer, and the other one isn't, obviously the juicer has an advantage. Does that mean said juicer will win? No. So steroids don't win fights. Am I typing in Chinese on accident? It looks like English to me and I don't speak Chinese, so I'm pretty sure this is plain English you're reading.
People have a lot of advantages and still lose. A chemical advantage is no different. Guys that are physically stronger get out grappled, guys with a serious ko power advantage get ko'd, and guys with a big height and reach advatage get out struck all the time.
An advantage is just an advantage. If it wasn't just an advantage, they would call it a guarantee. It doesn't mean it will win them the fight, it just means it gives them an edge. People with advantages lose all the time AT THE VERY THING THEY HOLD AN ADVANTAGE IN.
So no, steroids don't win fights. They help you prepare, but using them does not mean you're going to win.