There's a video on Youtube called "The power of VHS" which goes into the history of the VHS format and how it changed the relationship between people and entertainment media.
The speaker makes note of the fact that a lot of movies did much better in the home video release format than they did in the theaters, especially horror movies. He speculates about why that might be.
Without watching the rest of the video, I have my own guess.
For one thing, theaters are, well, theatrical. Even movie theaters. Going there is An Event, perhaps one you even dress nicely for, you are presumably there with many other people, the presentation is loud and large, and if you are frightened by anything, well, having lots of people around can be reassuring when you are all of the same mind about something. All this may enhance the experience of an action movie, or even a romantic movie, but it dampens the effect of horror.
But when you watch a movie at home, you can alter your setting. You can make it more or less chilling, as you please.
If you wish, you can turn on all the lights around you and wrap yourself up in a blanket and sit next to your bae and have some tea and watch the horror movie from a safe distance of contentment.
You can watch it alone. Late at night. With the lights off.