What we actually need is for the bad things they're doing to stop, individually and systemically.
I get it if someone thinks that can only happen with bad things happening to them, but there's a chance that's wrong, so keep the breathing room for the natural 20, and don't let yourself become part of a vengeance cycle where the means--the vengeance--eclipses the actual goal: shit being better.
That said, if that cat did the bad things to them I would give it treats.
This is true, but that doesn't mean retribution has no place. As a tool of terror, it can be quite effective. As a way to disrupt their ability to harm us, it can also be effective.