Billionaires are notoriously difficult to track. It’s no surprise – the easier they and their assets are to find, the easier they are to tax. But by all accounts, the number of uber-wealthy people in China is in decline. Of the world’s estimated 2,640 billionaires, at least 562 are thought to be in China, according to Forbes, down from 607 last year. With crackdowns on financiers and a roiling political climate, many of China’s rich people are looking to move their money, and themselves, out of the country. China’s elites have long looked for ways to take their money overseas....