Why would anybody want to join the US military?

Maybe the person has a general interest in the military. They don't have to do infantry, they can have a desk job or do nearly anything you can think of. The benefits are a plus, the pay is constant, and not to mention, college is expensive. College loans need lots of help paying off. Also, if you want a criminal justice job after service, that can be used as professional experience rather than policing. Whatever floats your boat. It's not all about the stereotypical soldier.