Many a decade ago when things were a bit less ridged, one of the customers of the casino I was associated with at the time happened to own a professional sports team. He also loved betting on his own team, but because of image and reputation he always did it discretely.
Over a dinner when the topic of his betting on the team came up he shared that he never understood why his team’s league was so against sports betting. His thoughts being that everyone likes to have “a rooting interest” in their favorite team by having a little bet on the game or, in the vernacular of the day, “some skin in the game.”
As our casino at the time did not have a sportsbook (back then not every large casino had one) he got his bets down elsewhere. I was never aware of him betting against his own team, but when he would not bet large on his own team, particularly when they were favored to win, it seemed to inspire several of his attending casino hosts back then to wander out and get a bet down on the opposing team with frequent lucrative results.