Yup, author did a good job with this, at first you are like "Really? Now he wants to destroy humanity outta nowhere, is he crazy? Then why he defeated the demon king? It doesn't make sense" but now, it's starting to make sense. He literally started to go crazy for having no purpose in life anymore with that peace.
Bro, how many redraws you did? Damn, thank you so much for your work dude.