It seems like such a terrible feeling to know you can't trust one of your neighbors. After all, they have keys to one of your two main protectors, the building door and your apartment door. Half the work of breaking-and-entering has been done for them, and they're in an excellent position to observe your comings and going. But even more than that, there's the constant feeling of unease and resentment. One of the people that you say "Hi" to or smile at every day does not have your best interests at heart, and is in fact actively working against you. Is it worse if you know exactly who's doing the stealing/vandalizing/etc, or is it worse to suspect everyone?
I tend to think of apartment buildings as tiny villages: we may not be friends, or family, but we're in this together. We all have to put up with the same thin walls, noisy street, and slacker landlord. We're all trying to keep ourselves and our families (and our stuff) safe, so I always hope that shared experience will buy us all a little empathy, a free pass from even those who steal and destroy other people's things. Not that I want them to go steal other other people's things- I just wish the neighbor bond was stronger. If you can't love thy neighbor, maybe just don't screw over thy neighbor?