Why are there so many TV shows about UFOs?

Why are there so many TV shows about UFOs? The Discovery Channel, TLC, and History Channel all have shows and doentaries about UFOs and aliens. I don't get it, they use "science" is in these shows to show that UFOs exist. Yet their "scientists" are already believers and they very rarely have real scientists that give contradictory views and almost never talk about how natural phenoms could be behind these sightings. I think they are just perpetuating the myth and are instilling in people that if you see something in the air that you can't identify then it is a UFO from a different planet. So why are there so many shows and why do these science like channels have them on?