The book "The Millionaire Next Door" [1] talks about this in quite a lot of detail. From my recollection, it's based on studies the authors have done. [1]: htt

The book "The Millionaire Next Door" [1] talks about this in quite a lot of detail. From my recollection, it's based on studies the authors have done. [1]: http://www.amazon.com/The-Millionaire-Next-Door-ebook/dp/B00CLT31D6/ref=sr_1_1?ie=UTF8&qid=1374668217&sr=8-1&keywords=millionaire+next+door http://www.amazon.com/The-Millionaire-Next-Door-ebook/dp/B00...