Do you forget that most of the bots are provided by Steem witnesses? Is a huge business, for a vote people pay a lot of money, so from one side they get their full vote in SBD or Steem, and then since their vote is so heavy it will bring an extra 25% as curator.
Thing is people is so greedy that they will wait until last minute to bid, making their money worthless and at the same time of those who play by the rules.