Thanks for finding a steel‑man way to interpret it. That is such a bizarre narrative choice I didn't even consider it. So they used that arrow notation consistantly to refer to the headings, representing the order of magnitude of money, the entire article, which was a great idea. Then for some baffling and unknowable reason, they decided to inform us that a count of people can also be expressed as a power of ten using the same notation.
"A person with lower ↑6 wealth is a “high-net-worth individual” (HNWI, $1m)"
"About 16 million people (↑7) are designated as HNWI."