the problem with police is that

• the people who should work as a police officer don't want to be a police officer

• the people that shouldn't work as a police want to be a police officer

I don't think police is inherently a bad thing. It just happens to be because people who want power over others should not have power over others.

similar story with politicians. I'd prefer an honest politician. but the process of picking them selects for those who are dishonest.