You clearly did not read your own article. He would only be worth that if he was margined to the hilt.

If he invested without margin then he would have made half of what he actually made. And that's without any spending at all.

First of all you're wrong, I did read the article. Secondly, the author directly addresses that point. He was leveraged when buying real estate too, so why not assume he would be leveraged up in the stock market? It's not an uncommon practice at all, and the comparison wouldn't make sense without factoring in loans.

Frankly I would have done the same, I think running a bunch of different businesses would be more stimulating than maximizing wealth through stocks. But objectively he's paid a financial price for that.