Selfish
Now selfish is a terribly overlooked word. It's easy to say you should NOT be selfish, but it's primary human nature to be selfish.
As I thought more about this, I realized that what you shouldn't be is overly selfish, to the point where only you matter. For people who are like this, misery is everything. They love being miserable - almost in a perverse way, where they want to be miserable and everyone else must pity them.
And then it hit me - overly selfish people don't take responsibility for anything they do. They'd rather blame somebody else or other elements of their life. So well, I guess all I can do is feel sorry for them and hope that they are happy being miserable.