Just because Joel still ends up being a selfish man, he does go through a pretty big arc, going from being a person completely detached from his emotions that pushes everyone away to finally accepting a bond with another person, to the point that he would doom the chance of a cure just to keep her alive and remain close to her.
I know people sometimes think character arcs are this thing where characters do a complete 180, but that's never reality. Joel's arc is actually one of the better, more realistic arcs I've seen in games. He's still Joel, but he definitely changes.