They benefit from the culture of worship, the endless hyperbole.. as do people who join the military. I seriously doubt many cops are really that paranoid.
They work themselves up into a belief that they're going to war every day. It's often part of their regular training.
Look at how many bullets are discharged by police on the regular. That one Miami car chase where they fired like 300 times and hit the car 20 times. In NYC where they fired almost a hundred times, did not hit the gunman but hit all kinds of bystanders. When they were hunting Dorner and fired up that car with two women that matched not a single part of the description.
That time in Arizona they got so amped up to serve a warrant at the crack of dawn that they literally ignore every rule of how to stand in fields of fire:
And yes, I will forever use this example if only for the dude who is standing back and runs over to lean in with his handgun and fire randomly into a house he can't see into. Because

And these are some of the first four I remember. Police should be de-escalating. Serving warrants when people leave the house, not using SWAT to deliver them afterhours. Their procedures actively promote paranoia because of how they deliberately increase the danger involved.