There will always be people that for some pathological reason just want to inflict pain, hurt, damage and annoyance on others, it is what feeds them and they delight when people are annoyed by it.
My experience is that when ignored on the whole they will go away,
Unfortunately though the technology of Bots means that set and forget can be implemented and some down voters do just that,
Even their initial reasons for instigating downvotes is forgotten, they just know they can wreak havoc
Yes, this
is our main problem... and some of the pathological cases here are feeding themselves with the problems (or suffer) of others... and we can't just wait for them to give up...