Even Though I'm Invincible, I Still Work Hard to Make Money

As all sorts of crises descended, the protagonist got carried away and went straight to the battlefield. After taking down "Sin" and getting into a few fights with Cthulhu and the gods, he sat atop a mountain of corpses and suddenly realized something: he'd been working for free! He wasn't getting paid!

With that in mind, he dropped everything and left the battlefield, embarking on the fast-paced (miserable) life of a wage slave.