The majority of them get into the job because they crave power, but are too thick to get into any other sort of powerful position.
And the type of people who crave power are the ones who really shouldn't have it.
My experiences with the police have been frustrating, to say the least. The ones that weren't corrupt as all hell were completely incompetant.
That said, I do not hold a grudge against police officers in general. Some of them really do only get into the job to serve and protect.
So rather than condemn the lot of them for being power-hungry thugs and incompetant idiots, I like to give them the benifit of the doubt.
Because I am totally fucking naive, it seems.