There are thousands of cases of people who have rejected their survival, who have put their own lives at risk to fight for ideals, for values, for freedom and for justice, and who show that the human is not a cold-blooded animal.
Genuine self-sacrifice is most common when parents are protecting their own children, otherwise it is more of an anomaly than "the rule".
Some are brainwashed with the "hero myth" which (dubiously) promises "eternal honor" in exchange for their life.
It is a matter of finding something what matters more to people than their own life to show that it is not simply a matter of survival (in that case life would be above everything). For some it is their children, for others ideas, for others religion, values, etc., even money, comfort, and the like, it is not always a good thing
CON-ARTISTS hijack our natural motives.
(1) PROTECT YOUR SELF = PROTECT THE IDEAS OF YOUR LEADERS/RELIGION/PROPHETS
(2) PROTECT YOUR FAMILY = PROTECT YOUR FELLOW SOLDIERS/ZEALOTS/ORGANIZATION
(3) PROTECT YOUR PROPERTY = PROTECT THE SYMBOLS AND RELICS AND TERRITORY OF YOUR LEADERS/RELIGION/PROPHETS
For example, "i am second". LINK