But to their culture, you're not a very good whatever to not be willing to sacrafice yourself for the betterment of the group.

Everything is a matter of perspective. You believe that the gods they believe(d) in are not real, but to them, it was. They were happy in their ways of life until the foreigners came in and forced their beliefs on them. Are/were they better off being forced to stop? No way to know. Soldiers in ancient times thought it was better to die in combat than escape to fight another day.