Some of those on Swat view it as a good paying job advancement.
The problem is that these people do not have any psychological training and they turn into power abusing lunatics. (see also kerry "do you know who i am.")
My observation is that power abusing lunatics are attracted to police work. Some are screened out and some make it onto the force. The latter then get to inflict their lunacy on the public until some scandal crops up. At this point sometimes their jobs are still saved by the police union or they transfer to a different town.