Does your use of “self-made" have any concrete definition?
I looked on the related website and the very first blog entry is about how you can teach your children the skills they identify as leading to wealth.
And yet, it appears that the claim is that, in general, people don't get taught these skills, and some people discover them through sheer grit and determination. Which seems contradictory.
And that's putting aside the weird concept where someone who earns 10 million and spends 9 million on stuff, is ranked as the same as someone who lives a meagre life and dies with 1 million in the bank. I'm not sure that concept translates well into the commonly accepted definition of millionaire.