I think a big part of this is because it is a massive circle jerk where everyone delegates to upvu and it gives out massive votes.

People like slowwalker making almost $400/day in votes due to this.

Steem power is extremely valuable as there is a shit ton being made by those who are in the circle.

Look at steemit.com trending. It is insane. Now think of the curation rewards being made sniping that bullshit.