> I just think there is some demand for jailbreaking, and lack of public demand isn't a significant explanation for lack of jailbreaking progress on iOS 10/11.

For the most part, I agree with this, and I was making this argument somewhere else in this thread: the primary reasons that we haven't seen many or, when they happen, "pleasant" jailbreaks for recent versions of iOS is that Apple has continued to be good about not having severe regressions in their attempts to secure the device, they have added really interesting mitigations ahead of the competition, they have changed their prioritization for plugging holes (they used to let jailbreaks sit around for months), and they've hired many of the more "mercenary" people who would work on jailbreaks away from The Resistance to work for The Empire.

That said, there is at least some connection with demand, and that's something worth examining in more detail here.

> ...after all it only takes a single determined developer/hacker to craft an exploit and deploy it for reasons not connected to public demand...

The way you word this sentence makes it sound like the work involved here is comparable--not just in quantity but in concept--to building a real-time chat application or some other slightly-complex web application. This isn't just "work": it is a combination of luck and skill that relies on winning a game that you are playing against an opponent (Apple) who had to make a mistake; if anything, it has more in common with panning for gold than building a bridge. One does not just "craft an exploit", no matter how determined.

The reason people are willing to burn tons of time into the possibility of finding a vulnerability in this platform is because there's a ton of PR and excitement to come from it, which is largely tied to the amount of interest that exists. There are tons of less secure devices out there that never get anyone bothering to "jailbreak" them due to lack of interest; people even take up bounties to try to get these devices hacked. This is made much worse as there really aren't that many people who can even pull this off when given an end-to-end explanation of a vulnerability.

What ends up happening, thereby, when there isn't much of a public interest in jailbreaking, is that these people spend their time working on hacking other devices or they hoard their exploits (as why bother burning your magic trick on people who don't even care for the performance?), whether for personal use (it makes a great parlor trick while also letting you do a lot of great research into the workings of Apple's software) or to sell for a profit (which might be to Apple through their bug bounty program or to a third party; the latter brings up interesting ethical questions, but people definitely do it: these exploits are then used either to do more research or are turned into weapons).

We can then ask "why has demand in jailbreaking decreased? as in, why does this matter?", and I see a few reasons: one is that Apple has started "throwing in the kitchen sink" (seemingly after waiting for Steve Jobs' body to be cold in the ground...), another is that the extremely killer and pressing needs have started to go away as Apple fleshes out the operating system as well as allows more things into their App Store, and another big one is a kind of "death spiral" that comes from there being less to do, leading to fewer people bothering to do it, leading to less reason for developers to develop cool stuff, which is why there's less to do... this collapsing market is a really tough sell.