Many of the world’s richest countries are also the world’s smallest: the pandemic, the global economic slowdown and geopolitical turmoil have barely made a dent in their huge wealth.What do people think when they think about the world’s richest countries? And what comes to mind when they think about the world’s smallest countries? Many people would probably be surprised to find that many of the planet’s wealthiest nations are also among the tiniest.Some very small and very rich countries—like San Marino, Luxembourg, Switzerland and Singapore—benefit from having sophisticated financial sectors and tax regimes that attract foreign investment, professional talent and large bank deposits. Others like Qatar and the United Arab Emirates have large reserves of hydrocarbons or other lucrative natural resources. Shimmering casinos and hordes of tourists are good for business too: Asia’s gambling haven Macao remains one of the most affluent states in the world despite having endured almost three...