Then, voter 80 or 100 can come in and take another 5 or 10%, if they have a much larger stake.

30 or whatever still might get nothing, depending on how much SP he has, but he'll always do better for the whale coming in than he would have done otherwise.

That is to say, voter 30 never loses out when a whale comes in after him. (though if his stake is small enough, it might not be enough to actually get him a payout. but it will get him closer i think always). If he's not making money on a post with a faily high payout, its because he is dominated by the medium sized guys in postition 1-29.