If I'm not mistaken, he was in private law practice for a while. I've heard lawyers might make a couple of bucks. 

Beyond that, I don't really think about it. Maybe his wife makes a mint at her job, or he scored on a dot-com stock buy, or red came up at the Bellagio roulette table. Or maybe he bought the house for a modest price 20 years ago and it appreciated. (My own house is up about $35,000 since I bought it a year ago; relatively small potatoes, but you may have heard real estate values are up this year, although the article says he actually came down on his list price.)

Does it really matter?