Your whole theory is based on an assumption that you didn't bother to verify.
Interesting
http://www.mediaite.com/tv/john-oliver-eviscerates-bill-maher-in-the-ratings/
What's even more interesting, Mr. Spock, is by my calculations, you are wrong. But thanks for trying to fact check me anyhow, I guess.
http://insidetv.ew.com/2014/06/05/game-of-thrones-sopranos-ratings/
18.4 million average viewers beats Billy by 14.4 million viewers. And you really don't think that Billy is averaging at the bottom of the HBO production pile? In spite of what your first junk link claimed to the contrary? How about this link, regretably from last year, of the largest HBO audiences ratings broken down by series seasons. Hold on to your party hat, or whatever that is that your avatar wears, are you ready?
http://hbowatch.com/hbos-most-viewed-series/
Obviously, Billy is not listed, is he? Well, isn't that interesting. But still, his rating numbers compared to those "estimated" numbers leaves him at the bottom of the HBO pile and certainly not a "top performer". Unless "top performer", to HBO or media spin doctors publishing sensationalized hype on the web, that really means "cheap to make", inspite of the lackluster ratings. Which is a lot more accurate than "top performer".
When I had HBO I would often leave it on for hours and hours while doing housework, eating, working or playing on the PC, whatever, and at some point, Billy would invariably come on. So was I considered a viewer of Billy then? When I had a Neilsen box for a while, I guess I was sort of half assed watching him, by default. Just a little primer to put those ratings into some perspective for you.
I also just found this interesting HBO ratings nugget, since you sent me on a valiant search for Bill Maher's HBO ratings truth. It don't really say much, other than to suposedly reveal HBO isn't as ratings conscious as some networks are, which is of course, an utterly false premise to begin with. Of course they are ratings conscious. But the real hot button question, at least to me, is: Are they gaming the ratings numbers?
http://hbowatch.com/traditional-ratings-numbers-dont-matter-as-much-to-hbo/
And here is my slam dunk on you. HBO has 114 million viewers, and Billy averages 4 million a show. Those are pretty shitty ratings for HBO by any standards, looking at subscriber numbers, and that means he certainly isn't a "top performer" for them. And do you think they will make any money off his old shows on dvd/blu-ray sales? Not very likely.
http://mobile.businessweek.com/articles/2014-02-05/hbo-finally-reveals-profit-numbers-dot-take-that-netflix
Remember that I said he was probably one of the lowest rated shows on there, and that statement was originally based on knowing the Game of Thrones ratings and his ratings already or I wouldn't have said that. At any rate, all these links, especially with the last one listing subscribers, seals the deal from "probably" to "certainly" one of the lowest rated shows on there.
Thanks for clearing that little miscommunication up, though.