I loved the first Von books. He and Sagan were among my favorites along with Lewis Thomas, Stephen Jay Gough, John Fowles, John Steinbeck, and a few others.
Von was a teenage boy's distraction and a little critical thinking and practical experience made me question many of the artifact interpretations he made. However, there are real questions about the age, and method of construction, of some mega-monoliths, desperate things like the Antikythera Mechanism, and sites like Göbekli Tepe.
Seeing Von was a claptrap I kept reading UFO literature as if it were fun fiction. Until the 2016 release of the TicTac video, it was back to taking the topic more seriously and evaluating some of my old authors. Especially my idol, that being Sagan. I started diverging from Sagan, I had read three of his books, some repeatedly, and found him coming off not as a physicist, though he knew astronomical physics, or as an inventor or creator. Carl's genius was not forward-looking but suffered elitist, siloing, and close-mindedness, and through his masterful telling why this "is" and that "can't." Not, a great mind's way to see the mystery of UFOs.
I had to laugh when after the movie "Oppenheimer" came out I stumbled on this:
Why the 'Father of the Hydrogen Bomb' Hated Carl Sagan
https://www.realclearscience.com/bl...e_hydrogen_bomb_hated_carl_sagan_821874.html#!
Sagan's ideas need to be revisited and revised because physicists are moving into a world Sagan was not privy to, maybe he could adapt, but as things move on he is right less often. There are reasons he would not know extraterrestrial (?) life if he'd seen it as I think he was not open to it.