The private security business in the U.S. is a massive industry employing hundreds of thousands of people. These firms can range from security contracts at shopping malls, to former U.S. Special Forces soldiers who guard diplomats. Private security is expected to grow to an $81 billion industry by 2023, and that's just in the United States, according to the Freedonia Group. It goes way beyond security guards hired to protect industrial areas, commercial areas, and residential areas. And the industry is now going global.