I had a friend when I was growing up. She had a suburban modern basement. It was completely lined with concrete and ready for a pool table, even had some happy windows.
Not the one I grew up with.
Our basement was worse than any dungeon in a castle. A lot of folks grew up with these kind of basements. You know the ones; where mushrooms could grow and damp permafrost earth meets with walls made of stone and concrete and horse hair and chickenwire. Oh the horrors!
Basements seem to hold the most unease of any part of a home. Attics can be crowded and hot, but basements are cold, damp, and kind of tomb-like. The one I grew up with had rickety wooden ancient steps that bowed and creaked and were perpetually cold. On the right side was a wall but on the left side an opening to a crawlspace that contained hard packed earth and hibernating black snakes underneath the kitchen which was an added on room. That dark void would stare me down. Anything could be in there, even Pennywise (above).
At the bottom of the stairs was another set of stairs that led up to the flip open root cellar doors. To the right, a creaky old door that led into the heart of the chilly beast. The floors were concrete and uneven, a sump pump nearby was used after rains to empty out the ankle high water. Cobbled together benches made up my father's work area where all kinds of big angry tools sat and waited to work on some other thing that had broken down in the over 200-year-old house.
Supports held up the center of the room. Mother taught art and stored many of her paintings in this miserable place. Few of the survived the climate.
The canned foods were kept in the far corner of the basement. Sure enough, every day it was my task to go retrieve the goods. The race through the musty smelling basement to gather the foods and race back upstairs before whatever seemed to be lurking chased me was a fast sprint. I always felt like I just barely missed getting caught each time as I swung the door shut and entered the sunlit kitchen.
As a ghost hunter, I find it rare that anyone with a basement does not complain about it. Of course, they are often the holding place for all unwanted items and the place where wiring and plumbing and radiators and the like are stored. They lack lighting and a sense of the outdoors. They are damp and musty. They feel as if they have few exit options. They are tomb-like. All of these reasons unsettle people.
Is there, however, a reason we should be scared of basements?
Other than a hypersensitivity to mold or EMF coming off of exposed wiring, there's no higher incidence of haunting activity in basements. This is more than likely because (if you follow popular explanations for hauntings) people are not likely to die there or particularly miss that spot so much they have to haunt it.
Even though there may be no legitimate reason to fear a basement, we still will. Their very characteristics make it impossible to ever be truly comfortable.