I'm not sure where you are getting your information from. There are literally thousands if not millions of charities around the world. In the U.S. alone people gave $316.23 billion to charity in 2012.
Aside from donating money to charity many others donate their time to mentoring organizations for underprivileged children and adults. Every single day people go unnoticed helping others in one way or another. We tend to see or find what we (look) for.
However I see that you posted this question under "Gender and Relationships" - Single Life. Each of us (chooses) our own friends, lovers, and spouse. Everyone wants someone who (complements) their life. It would be impossible to look at all the people who are happily married or in relationships and conclude "people always tend to be selfish". People are falling in love and getting married everyday!
One of the most unselfish things a person can do is share their life with another. It takes courage to be vulnerable to let someone in.