They're only hurting themselves. People have been taking cameras and recording devices to events since it was possible to do so. Few, if any, get anything marketable. It's part of the social experience. To be able to say, "I was there, see..!!". The NFL has learned this lesson and spends a lot of money trying to make sure people have connectivity at the stadiums so they can share where they are and what they're doing. It's part of their advertising budget, to make the experience go viral and to encourage others to want to do this as well.