Ooooh.. i get what you mean now. Lol... your vote isn't affecting the value as you think it is. Especially popular posts like those. There are a lot of people voting on those so the values will fluctuate more easily. I'm pretty that when you do remove your vote it does lower the value since you've pulled your vote out but Im like 99% sure you don't need to worry about your vote costing people anything... unless you downvote/flag. That will have a negative effect of course.