Hey Lasereth!
The Dunning-Kruger effect might give you some great insight into why so many people believe in ghosts without there ever being any proof to support their beliefs.
Human beings in general have inadequate knowledge about how their minds, memories and senses work making us much more likely to misinterpret experience.
One of my favorite illustrations of this the spinning dancer:
At first glance she is spinning in one direction but with some focus you can make her spin the other way.
It should also be noted that people who claim to believe in ghosts generally don’t have a theory outlining the subject. Their beliefs are constructed from emotion. They believe that they’ll identify a paranormal experience based on feeling rather than having a pre-defined set of parameters. Not exactly a consistent method of gathering information here.
Compounding all this is not understanding scientific principles. People who believe in ghost often think that we must find a non-scientific way to explain supernatural phenomenon – whatever that may be.
Science deals with gathering data and drawing conclusions about that data based on a hypothesis.
The most obvious sign of someone who doesn’t understand science is the statement: “well, science never disproved ghosts!”
So we are left with people who lack a hypothesis on what ghosts might be and have no consistent way of obtaining facts about the subject because they don’t even know where, how, or even why to start looking.
Fascinatingly this doesn’t stop people from seeing ghosts. Rather than labeling experiences they cannot explain as experiences they cannot explain people draw baseless conclusions. Not our fault. The spookiest thing of all is the un-explained. The brain is wired to label experiences. We have trouble leaving things as blanks.