Downvotes take up voting power, but do not provide any monetary gains. That means that in order for anybody to be motivated to downvote, the desire to help the community must exceed the possible monetary reward. This works very well for minnows, but dolphins and whales are increasingly motivated to downvote less. I'll provide a scenario:
A whale like 
So he would get a feeling of satisfaction from helpeing the steemit community if he downvoted, but would that feeling outweight $130? He could reap curation rewards instead, right?
People like 
Downvotes should be rewarded just like upvotes. The first person to vote (either up and downvotes) gets the most money, and you get more rewards if you downvote after 30 minutes have passed. Downvotes have curation rewards paid out after 7 days just like upvotes.
I understand that the money doesn't magically appear. I think that downvoting rewards should be generated just like curation rewards, but then pooled and distributed to the downvoters based on voting weight and power as not to give any money to the poster. So if one whale downvotes a post at 100% voting weight and power and contributes $200 to the pool and a minnow downvotes at 100% weight and power contributes $0.02 to the pool, each shall receive $100.01.
It may sound as if this is not in the self-interest of the downvoters, but each subsequent voter shall downvote to cash in on the last person's reward. This results in large pools of people accumulating to downvote content. This causes the downvote pool reward to increase exponentially, so it may be possible to profit.
The whales are going to be the leaders of this downvote movement, obviously. In general we can trust that whales will be concerned with the health of the community and will only downvote when they see fit. There is also no monetary incentive for whales to downvote instead of upvote good posts.
However, I can foresee that this may cause chaos with good posts being downvoted due to politics between whales. When a whale downvotes, minnows will come flocking to him and mirror his every move. This may possibly be used as a tactic by whales to ruin competitors.
There is also a possibility that "downvote pools" may arise when the supply of normal trolls and spammers have all been downvoted out of steemit. These "downvote pools" would be trash accounts that serve no purpose but to make shitposts. These shitposts would then be downvoted just to read pool rewards. I do not believe the "downvote pools" will ever pose a large threat to steemit, however, because wealthier accounts are less monetarily motivated to do it than minnow accounts.
