[Mainan_Tagonist]

Are you talking about income or actual wealth?

Your income may remain constant while your wealth rises significantly (say... because your investments are doing well, because you inherited... etc). The two are often confused when talking about (tech) billionaires.

[DrSiemer]

Wealth, not income. The statistic is about net worth growth. Saying "that's wealth, not income" doesn't refute it. It just clarifies the mechanism.