Have you taken a good look in a bookstore or wherever people seek books nowadays? When I worked at Waldenbooks, we had a whole wall dedicated to simply supernatural/horror. I was working there when Stephen King was first published, but the horror genre already was very healthy.
I've been reading horror stories practically since I learned to read, whether in comics or novels. Some of my favorite authors work in that genre: H.P. Lovecraft, Robert Bloch, Edgar Allan Poe, Ray Bradbury, Graham Masterton/Thomas Luke, Robert Stallman, Robert McCammon, Bram Stoker, Ambrose Bierce, Stephen King, Anne Rice, and Eric Temple Bell.
When I started writing stories, some of the earliest were horror or a mix of science fiction/horror.
Actually, horror in all forms is exceedingly popular and has been as far back as I can recall. At some points, it had a bigger following than in others, but it's always been highly successful with people.
By the way, I don't care for romcoms that much and am not really a mystery fan. Each of us has favorites and topics s/he finds less interesting. If you were a horror fan, as I'd guess by "The Crow" icon, I'd think you would know how prolific horror writers always have been and likely will continue to be. Sadly, too much of what is written and turned into filmed stories isn't worth the effort. But, that's the same for any genre.