In my introduction post (link above) this is explained. By upvoting posts I make curation rewards. But these are not payed in liquid steem, but in vested steem power. In order to pay them out to my delegators I have to power down. So every week I power down and in one week collect the curation rewards. Then I distribute them to my delegators proportionally to invested steem.
If I would not power down, then my own sp would rise over time and that would be not zero profits.
In my introduction post (link above) this is explained. By upvoting posts I make curation rewards. But these are not payed in liquid steem, but in vested steem power. In order to pay them out to my delegators I have to power down. So every week I power down and in one week collect the curation rewards. Then I distribute them to my delegators proportionally to invested steem.
If I would not power down, then my own sp would rise over time and that would be not zero profits.