The song "Straight On" by Heart contains the following lyric:
what the winner don’t know, a gambler understands
What does that mean?
I think it means someone who has something (the winner) can't understand the motivation/drive of someone who will put themselves at risk to achieve what they want (the gambler). In the context of the song, it would mean someone who has found a relationship/love won't understand why the singer would be willing to get hurt just to see if they can make it work with the person in question.
Risk management. The winner wins because he knows how to play with risk management. He isn't carelessly making his bet because it makes no sense, but that's what the gambler knows. The reason he isn't winning is because he's gambling. Think of it as opening a business. (Winner) You go through school, learn Financials, taxes, cost ext ect... (gambler) see you doing what you're doing with no experience and think it's easy because you make it look easy, opens an identical business but fails. <--- this would be a case of what the winner does know, the gambler doesn't understand