Betting on your favorite team
When you are serious about betting on sports, you need to set aside your status as a fan of a certain team and bet based on the expected value of the bet. Sometimes this will mean betting against your favorite team. I have a friend who loves the Dallas Cowboys. He literally places a $100 bet on the Cowboys every week. He almost always has a losing season. The book sets the point spread in such a way that my friend has a roughly 50% probability of winning that bet every week. But they also require him to risk $110 to win $100.
So my friend loses $110 half the time, and wins $100 the other half. That’s losing proposition over time. If my friend were smart, he did look for opportunities to bet where the book has a point spread set that’s inaccurate in one direction or the other. Then he’d only bet those opportunities, regardless of who the Cowboys are playing. Some weeks he might not even bet on the Cowboys game at all, while other weeks, he might bet against them. He might even get to bet on them to win once in a while, but his love of the team wouldn’t be a deciding factor in how he bets.