It is stake weighted

Someone with a large stake could split up his account and upvote and get consensus no? Do you know the exact calculation formula?

Fair point, although as the system gets large there is a reasonable argument that no one is really going to invest in doing that enormous amount of work. Sites like Facebook pay teams of people dedicated to handling hardcore abuse (such as posting child porn). Adding self-voting reward abuse to the task makes it even more challenging. In Steem there is no incentive to do any of this downvoting work. It is somewhat viable now with 1000 posts/day but with millions or billions of posts per day who is going to do it?

Lots of people run bitcoin full nodes to verify transaction, they have an incentive to do it because they have a stake in it and it's their best interest that the system is working properly because it increases the value of their investment.

One thing this debate has revealed to me... is that lots of people seem to think the best way to increase the value of their account... is by behaving in ways that earn them more STEEM rather than by behaving in ways that raise the price of STEEM.

This is exactly what I think people need to stop thinking in term of more steem but in term of raising the price of it.

Users will downvote content because it will make the value of their steem more valuable. Downvoting abuse, means more rewards for genuine content, which means more value in the platform.