Why are people like this?

I was on this finance subreddit recently and I made a post about Bitcoin overtaking Silver. Then somebody commented saying Bitcoin has no intrinsic value and it's going to zero. I told him, if Bitcoin overtakes Gold's marketcap will he change his opinion. He said, no. And then he started making fun of me and others joined. Why are some people like this? Isn't the definition of critical thinking changing your opinions in the face of changing facts? Then why are people so stubborn and arrogent?