Can't say I really blame him for this. It's like Dr. Manhattan or Q from Star Trek. When there's no where left to go, an eternity of boredom begins to set in. An existential crisis. The trick is finding some way to pass the time. His method is relatively benign than say, Zeno from Dragon Ball Super (although that worked itself out in the end). And he's pretty even tempered, only targeting those that come after him, and even sparing some repentant pawns or those that didn't have a say in the matter, like the roaches.