Heard of that book. I have several pilot friends, and one only sees their wealthiness if you’re at the airport with them. Some have a couple planes, like a Pitts Special and a RV-12. And their hangars — man caves on steroids. Great places to hang out!
It is a very good read. One example is a fellow who owns a dry cleaning business. Drives the same car for 20 years. He is very frugal and ends up very wealthy and no one sees it.
I have seen guys who are dead broke and present themselves to the world as very wealthy guys and the same in reverse.