I think the word The Millionaire Next Door used was frugal - not cheap. Look after the pennies and the pounds look after themselves. Millionaires in making do not waste money especially not on flippant things. That does not make them cheap - rather smart.

An important factor that is discussed in The Millionaire Next Door is the attitude to borrowing. It links to frugality - millionaires in making do not borrow to buy flippant things or to show off. They borrow to build their businesses or fund their education or training or hiring the best staff.

There is one aspect that is not covered well in either of the research pieces is to understand how many professionals become millionaires. Becoming a professional (e.g., doctor, lawyer, accountant) requires brainpower. Building a great professional business requires all the entrepreneurial power you describe - I know as I did it. A professional does not have to build a professional firm or an owned business to become a millionaire. Find the right business to work in and build it to a great business and the rewards can flow. I know as my father did that as an accountant who then worked as a business manager for a great business.

What I do know from those two stories. Brains helps. Determination helps. Builiding a great business (owned or not owned did not matter) helps. Frugality helps. Limited borrowing helps. And I know there was nothing inherited. My father started with nothing. I exiled myself fromSouth Africa with nothing.