Couldn't have said it better myself. Everything we do, we do ultimately for our own gain.
EVEN PHILANTHROPY. We do it because WE WANT TO FEEL GOOD ABOUT OURSELVES!
I'll state it once and I'll state it again--democracy and capitalism are flawed systems. In a world in which everybody was perfect and wanted his neighbor to feel happy even if it would mean his own expense, guess what?
Communism would work. There would be no need for central governments or the kazillions of laws in place as they stand.
Every single law in place is made to safeguard against the undesirable aspects of our own natures imprinted within us from before we were born through our own biological compositions.
So: "20 years for rape" is in place because if we see a beautiful woman, we instinctively think that we want to drop her in bed and make love to her. That law is there so that our self-preservation instinct overtakes our "screw every hot chick you see" instinct.
Communism would have worked in a perfect society. Know why Karl Marx and Frederick Engels are now seen as ideologues that brought the world a century of misery? Because they didn't account for human nature.
Human nature--account for it, and even if the resulting existence may be fucked up, rest assured that no ideological system can do better. They've all been tried--and failed.