That’s 18 people who own about a tenth of the US GDP.

Okay, sure. But that’s bad analysis. GDP is annual and net-worth is lifetime total. That’s also global wealth, not US-domestic (four of them aren’t even American).

Agree with the sentiment, but we should really be talking about global wealth not national income.

Something needs to be done

https://en.wikipedia.org/wiki/What_Is_to_Be_Done