Chu Yunsheng indeed began to regret his decision.
In fact, he regretted so much that he wanted to kill himself. He didn't expect that the scariest enemy was not the seven nails, not the death, but the endless loneliness and silence.
This type of torture was worse than death. It was like being locked in a dark room for many years, but there was no one to talk to and no one to listen to. It was just him talking to himself repeatedly like a maniac.
In the beginning, because the book was losing, and he was scared to be eliminated just like that, he was mainly focusing on helping the book to counter-attack the nails; and he didn't pay much attention to other things. But as the seven nails began to lose its advantages, and the risk of him being killed gradually reduced, he started to realise something else.