Sure, there are loads of Derek Acorah showbiz types geting rich on faking stuff on garbage shows like Most Haunted . . . . . . but I have no doubt ghosts exist for real as well. Those peole are like the "Nigerian Princes" on the internet who would like your bank details so they can deposit millions of dollars in your account . . . . they are fakes and charlatans, but it doesn't mean there is no such thing as 4 million dollars.
Too many people with no axes to grind have seen too many things that can't be explained away by the "it's all in the mind" argument - such as when the apparition or whatever is walking on the level of where the floor used to be and using doorways and staircases that aren't there now.
I have never seen anything myself, but have always kept an open mind on the subject.
Anyone who scoffs at the existence of ghosts just because they haven't seen anything themselves is saying "you are a liar" to a hell of a lot of perfectly normal people who have experienced things and won't profit in anyway by relating those experiences.