The Box Man's Solidity

The Box Man's choice to be alone rather than what is normally expected out of society is seen as something very unusual to many people. He is content with his life even though he does not have anyone to share it with. He found the dignity and and friend inside himself to realize that he didn't need others or material things to be happy. He chooses not to be with anyone because he knows that this is a solo journey that we do not need others to be happy with. And a question that I had was, why does society see solidity as something so negative?