I used to believe Son Goku existed because he has superpower to save the world with his friends (Z Warrior) and fight universe 7 warriors and fight the god of destrutions (hakaishin) of univers 7 and the others universes.
But it was before because I grew up and than it's the fiction/manga of akira toriyama and anime of toei animation
(studio animation japaness)
But when I speak about it , I am nostalgic of my childhood and seeing animation films me makes happy
A childhood belief about cartoons

others believed things like this
- I used to think that planet earth was the only thing that existed in the universe— Santiago
- I used to believe that everytime i saw a helicopter the A-team were in it on their way to fight the baddies!— Natalie
- i used to believe that if i wasn't nice to my toys, they would fight back.
Anon - I used to think an Afghan hound was a breed of terrorist dog that had to fight in the Taliban!Anon
- In my childhood I used to think that all the superheroes I saw on television existed in real life— Cris
- My sister believed the pork in pork and beans was marshmallow...and would always "fight" us for it.Anon