Most people who are into airplanes or boats scrounge by considerably to be able to afford one for leisure. Which is evident by the fact that he had to flip his hobby plane to fund a business purchase.
According to his father flipping the plane was only partly connected to funding the mine. He flipped the plane, and was only then offered the mine opportunity. He might have had ample funds for the mine regardless.
Either way, scrounging by to purchase a $300,000 luxury good (today's $ for the sell price of the plane) still qualifies a person as wealthy in my book, especially when taken together with owning the largest home in their area & his father's real estate & consulting business. It still means you had at least $300,000 in disposable income. Just because you choose to spend all of your disposable income on something like that doesn't mean you aren't wealthy.
