While I agree there are circumstances in which it is rational to risk one's life to protect serious values, I would not call that a "sacrifice", given the definition I previously mentioned. If a man risks his life in protection of the woman he loves, that is rational and moral. If a man risks his life for a complete stranger, that is irrational and immoral. Why should a person risk their own life for things unimportant to him?
Each person should orient their values that allow them to achieve happiness, which is possible.