Self upvote is another one. That should not even be possible. It's vain on normal platforms. But here is't a Problem.
If you are dolphin and above you can just make money by up-voting your own posts.
It takes away from any other curators if your posting is not totally worthless to begin with. And it takes away from everybody as there is only that many steem dollar generated each day.
Self upvote should be banned.
What's wrong with making a little extra money?
What is worse than self-upvote? someone with multiple accounts voting for own lame posts everyday.
Yes, we all know one of those. You only have to look at:
https://steemit.com/trending/cryptocurrency