I heard Däniken speak about 30 years ago, and exchanged a few words with him afterwards. He was a brilliant orator and came across as highly sophisticated. His arguments were contrived and I recognized that even as a child, but he was nothing like the natives of the YouTube era who do it for the likes and memes. He was completely sincere in his own belief of what he said.
He is a great showman in his way. He was far from being the first to write on this subject, but I think he was pretty much the first to popularise it on television.