obstinate
A person who’s like a donkey in a rodeo, they won’t stop fighting even when everyone else is already done.
My dad is obstinate. He won’t admit he lost the video game even when I beat him 10 times in a row.
My friend is obstinate. She won’t admit she’s wrong even when I show her the evidence.
My dog is obstinate. He won’t stop barking at the vacuum even though it’s just a regular vacuum.