I would be worried about organized crime. All sorts of sketchy things go on. The only sports event at my Uni where I wasn't able to photograph was college tennis because they have a problem with people past-posting on college tennis:

https://en.wikipedia.org/wiki/Late_betting

On one level I can understand the thrill of having some money riding on a game but I am baffled by the prop bets. Fixing a whole game is not so easy and rather risky, but influencing the silly little events some people bet on looks easy and hard to stop. It's particularly crazy that people bet on decisions by individuals and small groups as opposed to the outcome of a contest.