This is a very interesting topic because everything is so relative to your surroundings. I am a currently a two income earning physician family and can appreciate the skewed perspective the interviewee comes from. It isn't just Keeping up with the Jones' , it becomes what is social norm.
I grew up in a wealthy family(my father was a doctor) but thought at a young age my dad was cheap because he made me work for all my discretionary spending and "only" bought me a used Suzuki Swift at 16 yrs old.
When in medical school, I travelled in summers working off my "free money" credit line and went to underdeveloped areas like India and Southeast Asia. Very quickly I realized that the "poor" in Canada are wealthy by third world standards. I quickly saw most things as a waste of money in a relative sense and became ultra frugal.
Slowly as I have began working I see a slow creep of upper class mentality affecting myself and my wife in a relative sense. We still rent, drive modest cars and save ~75% of our income, but I still find myself justifying expenses by saying its only an hour's work equivalent. I also feel constant pressure from my middle class friends for not "living it up".
I should qualify this post by disclosing I do feel rich mainly because we never have to worry about money, although I'm not financially free and could stop working. I just think wealth/money psychology is so interesting as it is so relative based on individual perspectives.