According to your last video, the overall tax percentage is increasing with higher income (and more so the absolute amount of tax money being paid) in particular driven by the progressive income tax.
The 400 billionaires exception seems to be driven by "low % spending" on goods & services and thus the lowest % of consumption taxes. I assume capital gains taxes are counted as income tax? It seems too low considering that short-term capital gains are taxed at the ordinary income tax rate up to 37% and long-term cap gains at 20%, so how is that 9% billionaire income tax happening?
In the final graph everyone was pretty much at the same level, except the billionaires. For the data, it is all linked in the video-description on Youtube.
- the data can be explored yia: https://taxjusticenow.org/
- the NYT-OPed is here: https://www.nytimes.com/2019/10/11/opinion/sunday/wealth-income-tax-rate.html
- and the Vox-article with a lot more nice data-nuggets is here: https://www.vox.com/policy-and-politics/2019/11/4/20938229/zucman-saez-tax-rates-top-400