Anyone remember the "ancient astronauts" thing? Our science teacher showed that to us in sixth grade. I went home and excitedly told my dad about how "ancient astronauts" had visited the earth in the past.
He tried as politely as he could to talk me down. I couldn't understand why he wouldn't believe it.
Ancient Astronauts theories took big hits because their biggest advocate was Erich von Däniken, who was an intellectual lightweight at best, and a con man at worst.
Decades later the ball was picked up my a more credible (but certainly not perfect) researcher, Graham Hancock. But the damage to the basic theory was done by the ‘Chariots of the Gods’ and all the shallow spinoffs.