I could be schizophrenic (I don't think so, though...) but I firmly believe in the Fae and I believe I have seen them. It has been quite some time, as I saw them as a child, but I do believe they are more likely to appear to children, in general. I don't think of them as malicious or mischievous as others do, though. In my life, they have been gentle, guiding spirits. I could be delusional, sure, but it doesn't change the fact that I have had experiences involving the Fae which have positively affected my life. I don't think it's important to have proof, to know for a fact whether or not they are real. Just like angels and God and all the other deities people worship/believe in, if your belief does no harm to others and it's helpful to you, does it really matter what's real and what's just a fantasy?
That being said, in my personal opinion, I believe they are factually real. I still feel their presence when I go deep into the forest and meditate, and I actually think I might have been a fairy in a previous life. I feel such a deep kinship with them. I was even told by two different psychics that I had been a fairy in a past life and that they were still keeping tabs on me, in this life.