Based on the Global Wealth Book 2018 and 2019 from Credit Suisse, comparing Table 3-1 in both books, it appears that the number of adults in "under 10.000" range increased significantly in 2019. This is likely not a real change, but rather a change of methodology or data sources. As far as I can tell however, this is not detailed in the text. I have directed an email to Credit Suisse on this, as it's a rather interesting piece of data.

Quite interesting, curious what they have to say. I'd be glad if you can put me in cc (e-mail in profile).