One thing we think is the way of newsteem movement.
If we force someone to stop writing blogs for the reward with mass downvote,
it is not different from the strongest censorship, in my guess.

It really is totally different from the strongest (form of) censorship. The strongest form of censorship is preventing someone from publishing anything. That is the strongest form of censorship in existence. Steem has nothing of the kind.

Disagreement on rewards has always been an officially sanctioned reason for downvoting. Stakeholders collectively decide how much any given post should be worth in rewards. The #newsteem movement that was given rise following the adoption of the Economic Improvement Proposal two months ago has made use of the free 2.5 full downvotes available to each account. In my opinion, the result has been a drastic improvement of content quality in Trending.

That said, I have seen cases retaliatory auto-downvoting that has totally wiped out the earnings of some Dolphin-sized upstanding bloggers on Steem. That is reprehensible. The community should step up and heal those accounts immediately. Your situation is completely different as your rewards are still in the tens of dollars per post.

You say your rewards are proportional to your stake. Your rewards are still pretty good even after the downvotes. Another way to earn content rewards in addition to author rewards is curation rewards. Your stake is so large that you have a good chance of earning good curation rewards under EIP that introduced the 50/50 split between authors and curators. Because you're a whale, you will be able to earn several dollars with the click of a button if you have liked a post you have just read.

Do go on posting about Korean history and Korean temples. There absolutely nothing wrong with your posts per se. Because they have been exceptionally well rewarded, they have regularly appeared in Trending for years. That has drawn some downvoting simply because people have differing opinions on how rewards should be distributed, large ones in particular. In spite of the downvotes, your author rewards have still been very good. By curating content you find valuable, you have an excellent opportunity to do your part in making the whole platform more valuable while making pretty good money doing so. Your stand a lot to gain from that since your stake is still very large. Good luck!