Comic Book WIIFM
There are a number of reasons comics get cancelled, but not infrequently, it's due to low sales. The publisher -- even if that publisher is also the creator -- has decided that producing the comic is simply not profitable enough (or at all). They've expended as much as they feel they can do drum up interest and support, but it's just not selling well enough to justify continuing. Now, maybe that's because the book sucks. There is certainly no shortage of crappy comics out there! But it's possible, too, that it was a good book, but just didn't make it to the attention of the right audience. Bad or insufficient marketing, you might say.
Now, when a book gets cancelled, whatever money was transferred in that process halts. The creators don't get paid, obviously, but now neither to the printers, distributors, anyone the publisher had advertised with, etc. I'm not saying these people necessarily get stiffed money they're owed -- though that does happen -- just that there's no future earnings coming to them because of the comic. In the cases of larger deals, like through, say, Marvel or DC, most of those people will be able to switch gears and find other similar gigs. The creators shift over to other books, the printers pick up additional customers, etc. Smaller folks might have bigger problems. Maybe the creators have to do freelance ad layout work for advertising circulars, maybe the printer goes out of business entirely.
But regardless of what happens to these people, they broader comic fanbase still gives a collective "Meh."
It's not that they don't care per se, but if an individual isn't invested in the book in any way, they don't have a reason to put much emotional stock in the loss. They look at the book in terms of, "What's in it for me?" (In business shorthand, this is often abbreviated as WIIFM -- pronounced "wiffum.") "What do I, as a consumer, get out of whether this book continues or not?"
If a person was reading the book, their loss is direct; they don't get to read the book any more. Whatever they got out of it will no longer be available. And because they had some emotional attachment to it, they have at least some modicum of concern over the people involved. "Good luck finding a new gig, Creator X!" Frequently, these fans follow the creator on to their next project, if possible.
I don't know that anyone gives much thought beyond that. To the printers, USPS/FedEx/UPS workers who deliver the finished books, the comic retailers... I don't know that most people make that connection between any one cancelled title, and everyone throughout the whole process. Not that it's easy to -- we never hear about the guy who delivered the books from the printers to the warehouse, or the admin at the printers who had to juggle a bunch of invoices for any one project, or the teenager who unpacked shipping boxes in the back room of the comic shop... I don't know if their namelessness is an active way to make things emotionally easier on us consumers, or if we're simply unable to make emotional connections along those more distant lines.
But the question still boils down to "What's in it for me?" And while I recognize that at some level we have to do that -- we can't be equally compassionate about all issues everywhere -- it's a shame that more people don't extend their interest in comics beyond the handful of books they actively read.