Hata really likes to mix his humor and drama. Of course, money would solve all their problems. Though my favorite moment was when Nagi didn't notice the sandstorm.
"Brother... I did it again" Damn that line got to me. Considering where it comes from.
Now on to who destroyed the stone. The most obvious answer would be Yozora, but they would want to have the stone and not have it destroyed. Of course, unless they have an alternative (Which would most likely be Wataru). Other than that the only other person would be Isumi, but your guess is as good as mine as why she would do that.