In addition to what @hitmeasap said, the steem system is built on the idea that the community can correct misvalued posts. All of haejin's posts are potentially misvalued because the vast majority of the rewards come from two people. here's what the Steem whitepaper says about it. Keep in mind that this was written long before haejin got here.
Fortunately, any work that is getting a large concentration of votes is also gaining the most scrutiny (publicity). Through the addition of negative-voting it is possible for many smaller stakeholders to nullify the voting power of collusive groups or defecting large stakeholders
So it's shitty, but still kind of acceptable for him to upvote himself, but he should expect corrections from the community due to the added exposure he has garnered. Those corrections come in the form of downvotes. When haejin was downvoted, he lashed out and used his and Ranchorelaxo's SP to flag anybody that disagreed with him. This included charities and poker games. that is why he is so hated.
Haejin will tell you it was all lies and that he was defending himself. He will tell you that his followers were attacked, this is true. Not really something that I agreed with, but it happened and to some extent still is, I believe.
Thanks for the explanation on downvotes, it was something I hadn't really looked into yet. My initial understanding was that it's meant for spam and plagiarized content. Hadn't even clicked on the button yet.
Is that also the general public perception of downvotes? I'd assume most people would see it as some sort of personal attack, which it also could be in some cases.
It's well known among active members, but a lot of people take it as a personal attack. It really should be separate from a flag when it is just because of disagreement on rewards.