Having nothing to do could be a problem, but having too much to do could also be a problem. Jaekyung remained holed up in the Black Flood Dragon Archipelago, staying out of the Western Twin Lake's political situation, yet he still had so many things demanding his attention that he sometimes felt his mental energy was being drained.
If he weren't a Core Formation Demon King, and if his state of mind weren't superior to other Demon Kings of the same level, he might have already let go of one or two of the matters he was holding onto.
But because he had enough capacity to spare, he didn't want to give up any of it—his basic cultivation, his medicinal pill concocting, his dharma treasure designs, and his observations of the signs of the Great Tribulation stirring in the human territories. Picking and choosing is what those without ability do.
Those with ability have no need for such pointless worries. Then he could simply have it all. He trained in the Nine Tribulations Heaven-Ascending Art, tempered his body with the Ten Thousand Refinements Spirit Body, concocted medicinal pills, and at the same time, learned artifact refinement from the artifact refiners brought from Artifact Refinement Island.