I think that Mother Teresa was a person who was truly self less, she is very few and far between. The issue with people is we are greedy, and selfish. The human race has always been the have and the not. I would say my best guess this is why most are not truly altruistic.
Some people truly live to help others to say otherwise is merely looking at the surface. In fact,some people completely devote their lives to helping others. True it is not too common but some people are selfless. Of course there are basic survival needs but I'm not counting that to be honest because that should be just common sense. Also as for the majority of those over there who claim otherwise, I think you need to think about what you say a bit more I've disagreed with nearly everyone of you. There's a line between being selfish and surviving and I think some of you have gotten it mixed up. Especially the one who claims "nobody holds such virtues". To me "nobody" is a loaded word because your forgetting their is 7 billion people on this planet in counting, the many is not every.
No one is ever completely selfless because our basic human urges take over eventually. We need to eat, breathe and sleep, which can be selfish. Every humans has their own needs in order to take care of themselves during some point in our lives. However, some people can come close to being altruistic such as Mother Teresa of Calcutta.
No, nobody is ever truly altruistic, because when people do nice things, they only do it because they think it will make them happier. A wise philosopher once covered this topic, saying that people only act in their own self-interest, even when that self-interest is from having helped someone else.
Even amongst the biggest donors who display great altruism, there are none that are totally unselfish. I would count someone as being truly altruistic if they were giving so much money that they were left with just enough money to buy bare essentials. I don't know of anyone that goes that far.
I do not believe that anybody is ever truly altruistic. I think that while some people are more caring and unselfish, nobody ever really holds such virtues. I think there will always be some percentage of selfishness when it comes to the beliefs and principles of some people regardless of the subject.