Imagine your neighbor claimed to believe that there was a diamond buried buried in has back yard that's the size of a refrigerator, and you ask him why. You see him out on his lawn digging every Sunday with his family. Imagine how you would feel about his mental faculties if he said "well, this belief gives my life a tremendous amount of meaning. You don't understand . My family and I really enjoy digging for this on Sundays, and it has a remarkable bonding effect on us". Or, what if he said: "I wouldn't want want to live in a universe where there wasn't a diamond buried in my back yard."
It's pretty clear that these responses are inadequate - deeply inadequate. They're worse than that. They really are the responses of a madman or an idiot.