Another thing we should all keep in mind is that we don’t have to downvote them to zero. As they are still paying for upvotes as well they are only getting a percentaged return.
I’m no expert so I cannot say how much it is. Is it 10, 20 or 30 percent? But if we could just downvote to make their profit turn zero that should already have a huge impact. The more, the better because from this break even point bot usage will mean losses... At least for the people buying votes.