Yeah, I don't self-vote, but then my vote is not significant. I can imagine it must be quite tempting for larger accounts not to self-vote. It can only be an "ethical" decision, as one is free to do so. However, I agree with you... protecting the opportunity is paramount.
Yep, people can do as they please and so there's self-voting.
But because people can do as they please there's also those that deal with others they feel may be doing the wrong thing.