Entertainment. That's the name of the game. He practically invented the gladiator fights, one of the first sources of entertainment ever.
Every cultured empire relied on entertainment. And the gods, they lived for it.
Living for eons really can get boring. So they watch the lives of mortals, demigods, and even monsters for their own personal enjoyment. It was like their own little soap opera.
And every one had their own favorites. Aphrodite, his girlfriend, loved watching couples and love triangles. Athena, the egghead, watched over schools, especially the girls in them. When Artemis wasn't busy, she looked for scouts. Apollo and Hermes liked to watch pranks and fun parties. The dork of Olympus, Hepheastus, liked watching inventors and nerds and stuff like that. The big three loved to make bets on their sports teams.
And him? He watched the classics. Fights. Boxing, mixed martial arts, even wars. Any real, powerful god, watches them. Even the mortals loved it. Why else would they have continued to do it since the founding of western civilization?
But like any other god, they messed with them. Aphrodite "spiced up" their love lives, the nerd blessed her favorites, and Artemis went and got her scouts or cursed the ones that didn't make it. Things one and two either doomed the pranks or helped them, and "livened" up the parties. The dork blessed his favorite nerds. The big three fixed their games, and their wives went ahead and unfixed them.
He doesn't mess with fights. He prefers to watch them win or lose in battle on their own merits. That must make him different from the other gods, being like a spectator in the crowd instead of controlling the game.
But it's just another day of entertainment for a god.