Thank you for the advise on rereading but I already have several times and am still allowed to have/express my counter opinion.
Of course, as do we all, and you still could be right about how Harry turns out in the end. However it is very clear in Christmas Eve, that Harry wants to be a good parent to Maggie. It is also clear that Michael is his role modal as to what a good father should be and how one should act. Parents everywhere are flawed human beings, but a consistently good parent, isn't immature nor narcissistic.
It may happen sometimes,but they fight it. Harry knows it isn't all about him, he wants to bring joy to little Maggie so he continues the frustrating job of the bike assembly and finds the reward there. It isn't just Murphy's death that he is grieving, it is for all those who had died and got hurt. He felt their pain when they fought under his banner, he felt their deaths, I believe that too has changed him.. Yes, he will always be a smart ass, because that is who he is, a smart ass, however I think we will find him less immature in the future applying it. He is all about his daughter, he knows he has been arrogant, he knows it isn't all about him, and he is striving to do better.. So maybe you don't have hope for Harry, but I do, or have hope that he is headed in the right direction.