I will just wirte similar same response as I have given "wakeupsheeps", in case you didn't see above reply:

You don't get the sliding scale till 500 but also your vote is worth 1-5 cent until then,so by not voting others but only themsleves you don't earn anything. That even more supports the fact that you should vote at leat 30 times a day. It is not just about money here. It is about showing appreciation and support towards other writers' content. Top show that they have loyal following they can count on when they post something, regardless if they earn much from that support or not.
IMO, if soemone is greedy holding their power over 80% or not voting more than 10 votes a day, then they should not expect other to be altruistic towards themselves and reciprocate on their posts.
Also, the power never goes lower than about 30% regardless how many votes you have cast.

Self post voting is a must. Self comment voting is a no-no.
Also commenting on others post without a vote is considered greedy or smap commenting to fish potential following or vote back while not giving anything.
Unless the comment was a criticism, thenthere is no need to vote on the post you don't like.