Yes, back to topic!
So far, it looks like:
1) Most people would in fact buy a game in a store, if it were available
2) The sweet spot for most games would be around $20
This means that for a dev, the Patreon model is in fact more profitable. With Patreon, you'd pay on average maybe $5 / month for a period of, on average, maybe 18 months. That's $90, and there are no guarantees that the game will ever be finished.
Obvious, at least for me. But then "more" profit isn't the right description about it.
First it is more on supporting the dev, than buying his product. For this you can wait till the game is finished / near finished and the pay the lowest tier to unlocked the game. Would cost probably 20$ (4x5$), so it is the same as for the "one time buy".
Other than that: Normaly a fresh released game cost - a least in my country - about 50$ or more (Triple A titles) in a retail/online store. From this 50$ the company that develop the game will see less. How much I don't know. I believe on Steam that are 30% from the number, so you "only" earn 35$.
But of course then such a title will, probably, be sold a few millions. So you would received 350 millions if you sell it 10 millions time. Again the development budget of such title will also be in the milliions.
Even if you have a small game title and your production budget was a lot less, then I assume you would also sold not as much copies as the big triple A title with a commercial budget that most likely cost more than the indie game you have made.
All of this game have the problem that you need money to develop and you must earn at least this money back when you release your game.
If you are a one men/woman show in my country, worked 1 year on a game, then I say, you must at least bring back ~50k and then you are on square one.
I believe most devs want to develope. Even if you are the most gifted dev around the whole earth, one people has its limit and the day have only 24h. So, if your next idea is bigger than you can work on it yourself you must hire other people. For this you need money and, more than that, credibility.
I wouldn't take a job from a new dev without any history and a tight cash reserve - as a regular job.
Therefore the monthly payment variant. It enables a lot of the dev to invest some more time (or resource) in they game that they could not do otherwise. As a double edge sword, as it is, the patreons are on the development aspect the same as share holders. The will take some of your freedom away frrom the development process.
And the porn game in the open game library. When a "real" porn game - not the soft one, who already are there - would be available on shops like PSN and so, I would by it if it's fit my taste. But would prefer a boxed version and if it really fits my taste a want a collector edition like the old ones (Lunar, Arc the Lad) - not so scam ones that have 1-2 digital goodies and nothing more...
As for me, if this kind of game would be appear on the usual video game consoles, then it would mean that we can finally pay and play this kind of games and show the respect as open as all others.
For the record: 20-40$, but depends. If it is my *perfect* game that is on the website or the shelf in the shop, without any previous knowledge about it, only the information of the case available, then 20-40$. Because I would have my doubt if it's a real deal or only some rip-off.