But it is very wrong to think that they don't exist just because you personally have not seen them. It's the equivalent of someone saying, "Love does not exist because I never loved anyone."
It is also wrong to say they do exist because you THINK you've seen some. The human mind is way to capable of fooling itself. For you to take it for granted that you saw ghosts when so many others have not seen such things is careless.
Why do you suppose that I have never seen a ghost in my 60+ years of life. Are they afraid of me? Do they think I'll go boo and make them soil their sheets?
Like everything else that would have to exist outside of accepted norms, ghosts are unprovable. Gods, ghosts, Loch Ness monsters, bigfoot, leprechauns, fairies. We humans have a million of 'em.
It is far more likely that you think you've seen ghosts than it is that you actually saw some. Far more likely that you'v been fooled by yet another fantastic claim than it being something you actually experienced.
I don't doubt that you think it was real. As long as truth is not one of your priorities, you are probably willing to accept anything fantastic, Obamacare not withstanding.
You saw no ghosts. You think you did. That affects your ability to function on this planet. Which explains your unpopularity around here. It all ties together nicely, and explains far more about you than most of us want to know.
And any ghosts reading this, hey, join up and PM me. Tell me how I'm wrong. We'll arrange to meet and then we can see who is the scariest amongst us.