It's not a peculiar warning at all. And they actually explain midway why. Large events are used as cover to find tourists such as NASCAR, the super bowl, solar eclipses, etc.. These places are just easy money with people they'll never see again and they can move onto the next event. Always under the radar. The cops are just left playing catch up. They have absolutely horrendous interagency communication. These people are not stupid, and I'm assuming some of them are in groups that have been doing this a very, very long time.