Can someone give insight about this...?

All of my life my dad has never been accurate source of information. He invents things he thinks are right and fully believes them. If you tell him information he will only retain half and invent the rest of it up. For example, if you told him “I went to the store and saw a dog on the side of the road” he would then later on tell someone else “Beth said she drove to the store and hit a dog and it died on the side of the road.” And he will FULLY believe that. If you confront him he will get defensive and say “no that’s exactly what you told me!” He has done this my entire life but it is getting worse as he’s gotten older. He rarely has correct information about anything or anyone. If he hears on the news “gas prices are high” he will turn around and say to you with a straight face “the news said gas prices are high and the world is going to run out of gas in a few years.” Like no, where did you get that second piece of information?! But like, he fully believes this and will not listen otherwise.

What is this? Why does he do this?