You're quite correct. Neighbors can be terrifying, because you never know just how unstable or irrational they might be, especially when certain common decencies have already been competent disregarded.

In the house next to me, there's a few teens/very young adults. They sit on their porch smoking all the time, and flick their butts over the fence into my bank yard. Like, WTF, who does that? At first, I quietly would clean it up and hope it would stop. It got worse. I made attempts to talk, but they refused to answer the door, despite it being obvious that everyone was home. I wrote a letter, being as extremely polite as I could be. This whole time, I am genuinely scared of the response. Not because I am socially inept or nonconfrontational, but because they have already displayed that they are rude, and rules of social interaction don't apply to them. So what's going to stop them from deciding I've insulted their honor and it's time to go to war? Key my car or slash my tires in the driveway at night? Salt my yard? Smash windows? Graffiti the walls? Rip up the flower bed? Or worse, harass my wife while I was working out of town.

What finally broke it was that I'd just throw all of the butts right back over the fence. Y'all can clean it's you go, or litter your own damn yard. Still took months of that before it sunk in. I held my breath every time, waiting for repercussions.