I consider someone rich who has the luxury of not working and still maintaining a very good lifestyle. In Silicon Valley you can't do that without substantial net worth.
The reason why we don't consider ourselves rich is because both my wife and I have to work very hard. We love our jobs and don't mind working hard, but we do have to work very hard. My work-life-balance is better than my wife's so I do more of the child-rearing, but I still jump online to finish some work after the kids are asleep.