I've seen people getting retaliation votes and stopping to use their downvotes as a result. And I've seen a lot more who got even more dedicated in keeping their efforts up.
I don't know of anyone who left because of retaliation. It's easy to avoid by keeping out.
FUD is always a problem. One more thing a lot of the targeted people don't get. Spreading FUD about the downvotes helps as little as self rewarding. Their greed makes them so focused on themselves, that nothing else matters. It seems they'd rather see everything burn than changing their ways to work together as a community.
The problem is, I for one don't like to be bullied into changing my ways. Convince me if you can, by all means.
Yes, I admit freely, I have begun to feel that way and - just in case - reserved the domain http://thetruthaboutsteem.org/ on a server where I can't be downvoted into oblivion. That's how fed up I am with people mingling in my affairs! On the flip side, I have also canceled my power-down, to keep my options open. I'm finding it difficult to decide what the right thing to do might be. As one commenter said earlier, good things don't need reasoning, they stand on their own merits. That really got me thinking...