It seems that police departments are always hiring and recruiting. When the economy’s bad and unemployment’s high, some young adults sign-up simply because they need jobs. It’s not easy to work as a police officer, but it’s steady work with decent pay and good benefits.
Beyond that, it seems that some people are just well-suited to joining police forces. They enjoy the “brotherhood” and camaraderie of their fellow officers. They’re comfortable dealing with confrontations and disputes, and they don’t shy away from challenges or danger. Also, it’s not so bad to have union representation when negotiating pay, working conditions, and grievances.
Police officers do seem to burn-out quickly, though. Even those who truly love the job are tired and ready to retire when the time comes. Aside from the high-ranking officers, I don’t think I’ve ever met a police office who’s lasted for more than 20 years.