It's a fallen world, friend. We're all a bunch of wicked selfish little bastards, but we can feel what goodness really is, and we ache from the lack of it in the world, because we're of God. We try to soothe that ache with things of this world and it only leads us away from God. It's counter-intuitive, but if you seek God and eschew the greed, selfishness and hedonism, he'll start to work in you. That's how it worked for me anyway. I would challenge you to try to do something kind for someone else next time you're feeling down. Especially if it's something you won't get anything for doing. Getchu some Jesus.