Most of the time, these people would be apprehended by the authorities, as indecent exposure is usually a crime in most states and countries.
Seeing the reaction that these people show when an exhibitionist flashes his dick, balls, or butthole at them is more than enough reason for them to keep on doing it. And if you've ever heard of the word exhibitionism, then you understand that it's just not acting in an extravagant way, but rather gaining sexual satisfaction out of showing your body parts, particularly your genitals, to people who are in no way related to you. According to the dictionary, exhibitionism is the act of behaving in an extravagant way in order to get other people's attention.
