Bejing is a province-level municipality: https://en.wikipedia.org/wiki/Direct-administered_municipali...
> A municipality is often not a "city" in the usual sense of the term (i.e., a large continuous urban settlement), but instead an administrative unit comprising, typically, a main central urban area (a city in the usual sense, usually with the same name as the municipality), and its much larger surrounding rural area containing many smaller cities (districts and subdistricts), towns and villages. The larger municipality spans over 100 kilometres (62 mi). To distinguish a "municipality" from its actual urban area (the traditional meaning of the word city), the term "urban area" (Chinese: 市区) is used.
A like to like would show a much different comparison as the wealthiest parts of New York are outside the city proper.
This is really a shame as there's an interesting story to be told about the recent growth of billionaires in China (and elsewhere) but it's been buried under a glop of poor reporting and wild comparison.
But do the billionaires live there, or are they in multi-million dollar penthouses in Manhattan? You'd think people like that would concentrate in the most prestigious areas, so trying to adjust the comparison like that may not yield a much different result.
North Jersey (especially Bergen County), Long Island and Westchester mostly. I'm sure there is some overlap with penthouse owners too.
If the BBC means the municipality itself, then their headline contains a Russell's Paradox (BR himself used a barber, not billionaire). In this case, regardless of the BBC's title, HN should insert "other" between "any" and "city".