Selfishness is the foundation of capitalism, individual rights, personal property, etc. If selflessness is so good, why not just have communal property and a moneyless society where everyone is equal and receives equal benefits?
EDIT: The correction was a bit tongue-in-cheek, Laguna. As an American, I'm obligated to a certain level of self-important nationalism. Maybe other Americans are losing this sense, but I'm sure my breed isn't altogether dead. In all honesty though: if there were a more American (in the sense of ideology rather than mere nationalism) country than the USA, I'd jump ship and move there.