[The Once-ler is silent for a while, continuing his trudge back towards the caves. Eventually, though, he deigns to answer her]

It wouldn't have mattered. In case you've forgotten after being locked up for so long, it's not like I have a great deal to live for anyway. [Most of his friends here are gone. Escaped to the deadzone, or gone home, or angels or...dead. And he has nothing waiting for him at home except five decades of loneliness and regret. He literally has nothing to lose]