I’d change that to “The kind of person who successfully becomes a cop…”.
I think a lot of people want to be a force for good, and the intent behind police as a concept is to reduce crime, and crime is generally bad. So a lot of people want to be cops to make the world better. But that’s like wanting to be an honest politician. Most people already playing the game are there for personal power, and if you don’t lie and cheat you won’t have as much power as those already in place.