My friend, if you believe that mythical creatures are real than you will one day see one of us. If you forget and stop believing than you will never see and/or notice us among you humans. It is also a habit of imagination. If you asked me, mythical creatures are real. For I am one myself.
You would like to keep a fire breathing dragon in your house? Be my guest...
The answer is not why it is do you believe they are real if you do then they are real who's to say that they arent
I do believe that some mythical creatures were once real and walked this earth as i have seen their spirits that now live on in the spirit realm.
They aren't real, and that is why they are called "mythical" because they are just figments of the imagination.