That book was originally written decades ago. Its threshold corresponds to about $1.7 million in savings in today's world. Their median was $1.6 million, or about $2.7 million in today's dollars.
And given that the people who attained that status on average lived in cheap neighborhoods, the fact that their income wouldn't stretch long in an affluent neighborhood isn't really a concern for them.
According to the statistics that they gave, an estimated 3.5 million Americans were that wealthy. In 1996 the US population was around 270 million so we're talking about the top 1.3% of Americans by net worth.
That’s what a a median of $1.6 million and a minimum of 1.0 million means. Half of their population was 1.0 to 1.6 Million the other half was over 1.6 million.
And given that the people who attained that status on average lived in cheap neighborhoods, the fact that their income wouldn't stretch long in an affluent neighborhood isn't really a concern for them.