Why did dally think he had nothing to live for anymore?

Dally felt he had nothing to live for after the death of Johnny, who was one of the few people he truly cared about. Johnny represented hope and innocence to Dally, and losing him left him feeling empty and purposeless. Additionally, Dally had a troubled past and a life filled with hardship, which compounded his sense of despair. In his mind, without Johnny, there was no reason to continue fighting or to hope for a better future.