I've tended to think that a lot of it is about different social circles. If everyone you know makes $50-100k/yr, you feel fine making that yourself, and may not even be sure what you'd do with a million dollars. If your social circle is full of millionaires and multi-millionaries, all of the sudden making a million feels like barely getting by and you think about all of the cool stuff you see people around you getting that you could get if you had tens of millions.