I think Erich Von Daniken should be coupled with Zecharia Sitchin and his Earth Chronicles. All believable stuff (up to a point) but they misinterpret and mistranslate what was left behind, was said or what was written to the point of distortion. Sitchin worked on the Sumerian clay tablets and although his writings are interesting and up to a point believable, he misinterpreted and mistranslated what was written on them. What I've always wondered though was what caused the Sumerians to write the things they did?

It's been said that all legends have a basis in fact but as we know (we do don't we?) things that are initially handed down by word of mouth have a habit of getting changed along the way.

As to why the "drone UFOs" are being allowed to become "accepted" as alien craft, might not that have something to do with not letting those who might become an enemy know what you're really up to and how advanced what you're doing has become?