I find it polite to say hi & “how are you?”. Then I realized they all give me the same answer. “Good. How are YOU?” Either I reply back or just keep walking, not replying with anything. Maybe next time I’ll actually stop them & have a conversation. Who knows… maybe the person is about to commit suicide & by talking to me, I save their life! Or just keep the same routine. Cause I guess just like them I don’t really give a crap.