obstinate
A person who refuses to back down even if they’re clearly wrong and everyone else is laughing at them.
My mom is obstinate. She still thinks the 2000s were the best decade even though everyone else thinks it was the worst.
My brother won’t admit he lost the video game. He’s like, ‘You just got lucky.’
My dog won’t stop barking at the mailman. He’s obstinate like a stubborn donkey.