Yes I think you might be misunderstanding how it works. The full value of a particular bot's vote may be $1,000+ (that's USD value by the way, not what will show on steemit.com), however that value is split up among everyone who sends a bid in the current bidding round.
So for example for a bot whose vote is worth $1,000, if 100 people all send in a $10 bid in the round then they will each receive a $10 value vote. So the larger bots are able to handle both large bids and small bids at the same time - they just split up the vote value accordingly.
And you are correct that the bots are just a method of advertising. On SteemIt.com your business is your blog and advertising via the voting bots is an effective way of increasing traffic to your business. Ultimately the value of the content provided in your blog will determine what type of ROI you get from that advertising.
No, I understand how it all gets split up. Math is, kind of, my thing.
I suppose I'm more curious as to where all the value comes from on the back end. It just seems like magic to me, that that much value can refill in 2.4 hours. I guess I need to delve into the white papers to see how all this works. So much to learn and so little time...
But first, after lurking for a few days, I should write my introduce myself post and actually "join" the community. :)
Ah, that's a very different question - maybe this post can help explain it at a very high level, and if you're mathematically inclined then definitely read the bluepaper and whitepaper for more details.
Let me know when you make your intro post!