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.
My thought too. Don't they have slogans like 'don't tread on me' and such? I am pretty convinced you don't get that kind of wealth without standing on everyone you can.