I had one solution, but im sure there are flaws in it. So upvoting can be seen as sort of a margin long, because you are betting the post will do well and get a curation reward. Flagging could possibly be seen as a margin short so if the post goes down in value and other people flag, you can get part of the curation reward they lost. If you are flagging content that does well, instead of losing money, you can lose a bit of your reputation. If you have a reputation under 5 or something (just randomly chosen on my end) then you lose the ability to flag things.