Many people want a happy ending, it means closer to them. But there are many was to find closer in a story, many ways to satisfy that need. Sometimes a story is such that a happily ever after would be out of place. Sometimes just surviving at all is the satisfying ending. Sometimes dying for the right cause is the satisfying ending. In stories with an anti-hero, often times the protagonist does so many bad things that them getting off scott free feels wrong, so the protagonist must die in order for the karmic balance of the story to work out to a satisfying ending.