Selfish or selfless?

Are we here to serve ourselves? I feel like I've gradually learned that everyone on Earth will, in some way or another, serve themselves ultimately. It's all about keeping yourself happy, and although we may say that our goal is to help others, that makes us happy, with would be us serving ourselves again. I guess it's an endless cycle. To me, though, we're a selfish nation, a selfish continent, a selfish world. Maybe I should stop worrying about the way that other people treat me and just realize that they're fulfilling their ultimate requirement in life, to make themselves happy.