I have held this belief my adult life and see it proven time and time again. The only motivation to do that job with that level of stress is either seeking power/authority or very rarely some altruistic motivation. Which of those things do we hear about more?
I served in the Marines (infantry) and got out about 10 years ago. A handful of guys I served with became cops or US Marshalls or prison guards. Because that was the best job they could get with their skill sets. Lots of police departments, at least back then, were actively recruiting people leaving the service.
And as a civilian I'm old enough now to have interacted with many police officers in many different contexts in many different places across the US. One or two of them were power tripping psycopaths for sure. But the VAST majority were just men and women doing a job like anyone else.
You may not have given them a signal or any reason to feel safe revealing their true selves to you.
Could you explain your thinking here? Cops are, at least near me, paid quite well, have good perks, get paid a ridiculous amount of overtime, and have pensions. This, plus the power of the position, seems obviously attractive.