According to Kaggle's "Movies Dataset," horror films are by far the most advantageous genre of movie to make if you're a Hollywood studio and want a big return on investment (which is all of them, probably). The ROI of horrors compared to action, drama, comedy and animation is truly staggering when you see the data visualized.
The amount of money spent on horror films is super low by comparison, and if you manage to make something halfway decent (according to viewer ratings) you're bound to return a big profit. In fact, you could make something bad and still not have a bomb on your hands.
The fanbase is there, the cost of production is low enough and the risk is pretty limited compared to big-budget superhero films or rom-coms. Reddit user dpee123 compiled some charts that show the stark contrast between horror and every other genre of movie, which begs the question: why even bother to make anything but horror if you're a business? Maybe Jason Blum and Blumhouse Productions are onto something...
Via u/dpee123.
