"The first bias [in The Millionaire Next Door] comes from the fact that the rich people selected... are among the lucky monkeys... [T]hey saw only the winners. They make no mention of the "accumulators" who have accumulated the wrong things... There is a way to take care of the bias: Lower the wealth of your average millionaire by, say, 50%... the bias causes the average net worth to be higher by such... in adding the effect of the losers into the pot..."