When Chewbacca retired, he went to a rather backwards planet in the Sol system and lived in seclusion in the woods. The people of the area where he lived called him Bigfoot because they couldn't understand his language.
@Sylkykat Since Star Wars took place "a long time ago," I now have the headcanon that the Bigfoots are all Chewbacca's descendants. I'm assuming he brought his wife & kid(s?) to Terra with him. 😁