That's fine if you met some people who don't meet the profile outlined in the book. It's a statistical trend, not an ironclad law. Obviously once you get beyond a certain point of wealth the difference in price between a Toyota and a BMW becomes insignificant.

Rather than just anecdotes, the authors of the book did actual research and found that most people who have actual net worth above a million dollars did in fact get there by carefully managing their money, and conversely, most people who had the appearance of wealth in the form of expensive cars and boats, didn't have the actual net worth that it implied.

So, if you're judging someone's net worth by the things they happen to own, the whole point is that this is not a reliable indicator of how much wealth someone actually has.