Here’s one reason:

Daniel Goldman, author of Emotional Intelligence, giving a TED talk about compassion. He says:

“Why don’t we [help others]? I think this speaks to a spectrum that goes from complete self-absorption to noticing, to empathy, and to compassion. And the simple fact is if we are focused on ourselves, if we’re preoccupied as we so often are throughout the day, we don’t really fully notice the other. And the difference between this self and other focus can be very subtle.”

He touches on charitable giving, dating, and comsumerism. It’s worth the 13 minutes.