Aside from self-published books, there are also series which got published up to a point, but the publishers didn’t accept the next book in the series. (And no, I did not write either of these.)
I’ve read a lot of books, and it’s the only example I was able to come up with. I’m not aware of a lot unfinished series actually, just a) a few series which might not have an ending, and b) a handful of series I never finished.
Aside from self-published books, there are also series which got published up to a point, but the publishers didn’t accept the next book in the series. (And no, I did not write either of these.)
Always good to see data on such things, data which I neglected. That at least reduces the survivorship bias of observation.
I’ve read a lot of books, and it’s the only example I was able to come up with. I’m not aware of a lot unfinished series actually, just a) a few series which might not have an ending, and b) a handful of series I never finished.