There's a guy called haejin who's voting with a possibly stolen account called ranchorelaxo. He randomly votes up the top trending posts with 100% strength without reading them. I have a bot setup that does a lower value downvote to counter some of his upvote, so that trending posts don't get hugely overrewarded versus other posts.

The blockchain gives out a fixed amount of rewards, based on the token price. A downvote simply redistributes the rewards away from one post to all the other posts. So downvoting an overrewarded post just means other posters get a little more for their post. People are constantly upset about how some people's posts are constantly getting more rewards than other deserving posts. Downvoting counters this trend.