Elon Musk, the high-profile billionaire who has placed bold bets on driverless cars and space flights, is known for his over-the-top antics: He appeared in a Los Angeles court earlier this week, telling a jury that a Twitter message he sent suggesting a Thai cave rescuer was a pedophile wasnt meant to connote the words dictionary definition and was in response to what he viewed as an unprovoked attack.

But when it comes to his personal real estate, Mr. Musk uses the same strategy adopted by a number of the mega-wealthy:…