Dare To Aks Talk And News About Our Differences 
The short answer is ‘because they’ve been taught to.’ The longer answer is that survival is a group matter, and a group that has no members who will sacrifice for it (a nation in which no one will be a soldier, a union in which no one will go on strike, a church in which no one will be a martyr, a PTA where no one will pay dues) is a group that won’t last long. Most groups that command any significant loyalty are a lot older than one individual human life. That is, they’re descended from a group that people sacrificed for – and that’s why they’re here. So the question is not what the individual gets out of it; if there is a question, it’s ‘What is it about some groups that’s worth sacrificing for, often over a period of many generations?’
