The book is a bit dated, but one of the best books ever about the way millionaires really live, work, and spend (as opposed to the way most Americans think millionaires live). At the time it came out, it shattered the illusion that millionaires were glitzy spenders who inherited their money and blew it on fancy cars, McMansions, diamonds, blow, and Krystal (or whatever it is that rich people allegedly lavishly spend their money on).
I first read the book in the late '90s, just before we hit our first million.
It described me and my wife perfectly. We have good incomes, and a large net worth, but are still frugal and live modest lives. Our middle class neighbors and upper middle class (often broke-ass) co-workers have no idea we are multimillionaires (or, at least, most of them don't- I think a few have figured it out). We proudly "fit in" at Walmart :) Well, okay, that's not completely true, now that we are multi-millionaires, we've become "snobs" and shot at Tarjay- but only because Walmart is too darned crowded.