That's not the way it works. First, the long term real total return of the stock market is between 6.5% and 7%. Second, even if you assumed an 8% real return, because of sequence of return risks, having a good chance of continuing to pull the same inflation adjusted amount going forward without running out of money requires your initial amount to be well below the average. For stocks, historically, with a 6.5-7% annual return, you've been able to draw more like 4% of the initial portfolio, and then increase that for inflation each year, and only run out of money in less than 5% of the scenarios. Granted, that approach would leave you doubling your money in real terms in more scenarios than you'd run out of money, so that's probably overly conservative for somebody that intends to keep working. But even then an 8% withdrawal would probably be too aggressive.
Of course, if Ginn can put $1M after tax away, he should be able to draw $40k per yaer going forward, which should be a good enough supplement that he can do whatever else he wants as far as jobs go.
