Enough people do care about pro sports that someone who doesn't still needs to worry about being caught in a riot should something like this happen. (they already worry about riots for real wins/losses)

There's also known relationship between sport betting and domestic violence.

The main relationship is to all gambling. Sports likely gets assumed to make it worse because people still believe the myth that the Super Bowl is the worst DV day of the year.

People sometimes do drastic things when they experience large gambling losses. They might embezzle, rob, scam, be unable to pay rent or debts. It has a significant effect on people who are not directly involved in gambling.