Cars and rockets are basically his hobby projects. I wouldn't be surprised if he put in 90hr from time to time because he wants to. He has the free time to do that. The dude is rich enough to afford help. It's not like his kids are missing meals because he's at work or he has to use the extra daylight savings day light to trim his own hedges and mow his own lawn. I'm sure he doesn't do it every week but he probably gets carried away and books himself for a 90hr week just often enough to remember why he doesn't do that every week.