Ah. If that's the goal, I suggest increasing the impact of votes the more upvoted someone is, and increasing the upness of votes the more often she downvotes relative to upvoting. If I'm popular and upvote a whole lot of things, that seems like a possible reason to weight my downvotes more strongly. But If I'm popular and don't vote for much of anything at all, it's not as clear to me why that's a reason to take my vote more seriously than if I were equally popular but participated in the voting system more. The latter just seems to discourage popular people from voting very much.

If we want to encourage our popular people to vote more, we should increase the power of their votes the more votes they make, rather than decreasing it.