You would be wise not to conflate one's general outlook on life with one's outlook on their football team. Especially if it is a football team with a historically inept track record.
Smart and mentally healthy people are able to compartmentalize those things appropriately.
Unrealistic optimism is associated with lower IQ and is actually linked in some studies to a tendency to engage in risk or unhealthy behavior. But science does have your back in that those who ignore reality do in general test to be happier. There is much truth in the saying "ignorance is bliss."
