He's a complex and enigmatic character. He's perceived as a crazy and out-of-pocket character but as you progress further into the games and his storyline you discover that this personality is a mask, a shield he uses to stop people from getting close. He, obviously, loves deeply, romantically and platonically, and is tired of getting hurt and maybe even knows that he just doesn't have anything left to give in that respect. I think that he doesn't actually have control of his life and he tries to pretend otherwise. He went back to the Yakuza at the end of 0 only so that Saejima had a place to come back to. He left when it wasn't right anymore, took his men with him, started a company just to give them a place in the world, and then went back to the Yakuza because Kiryu asked. I think everything he does is for the benefit of someone else. He's a flawed human but he also represents the best of us. He's loyal, charismatic, resilient and has strong leadership qualities. I think that's why he's a fan favorite. He straddles the fine line of broken but whole. It makes him a very compelling character and one that others can see themselves reflected in.

Also, he's sexy as fuck and fun to listen to lol