Most people think betting well is guessing who wins. It's false. Betting well is finding odds that pay more than your true probability justifies. You can be right on 60% of your bets and still lose money.
Expected value is everything
If a play has a 50% true probability but the odds imply 40%, there's value: over the long run, you win. Being right once is luck; positive EV, repeated thousands of times, is math. It's exactly the principle behind EDGE.