I think it boils down to: (some) People don't think about anyone other than themselves.

When the community around them is excluded, decision-making become very simple - just act greedily and selfishly! However, you and I know that selfish actions do not always yield the best outcome for an individual. We have more foresight than that and can reason to a higher degree how actions lead to a chain of consequences, good and bad.

Did we develop that awareness ourselves? I know I didn't - had I not been brought up with emphasis on civic-consciousness, I reckon I'll be one of those guys you write about