From a distant view the premise of the article is very much true. What I would be interested in, the article doesn't mention that it is included, would be how much he has pulled each year for expenses. Saying his actual current NW is $4b vs the calculated numbers if he had invested his $200m in 1974, 82, or 88 does not show the full picture. If his investments return 15% annually but he pulls out 12% the net of 3% will be less than the S&P500 and the difference will compound resulting in a large difference over the years.

I have no idea what the cash flows he pulled out each year, if any, are but would be interested in an analysis that includes all of these cash flows rather than looking at the beginning and ending net worth numbers and comparing to an investment that reinvests dividends and does not get touched.