Of course many Americans number in the 3.5 billion most poor people on earth. A lot of the homeless people I see everyday have about zero wealth. Hopefully many of them have something but I don't know what it would be.

Also, many middle class people, such as myself, have negative total assets due to debt. Because 'wealth' can refer to not only money but general capital (including human capital, which is what I have invested in) I would not say that my total wealth is less than zero, and I definitely have a lot of opportunity, privilege, and comfort. But if I was writing an article for the Guardian in order to rile people up about inequality, I think I could not incorrectly state that I have negative wealth, and by net $$ standards far less money than many of the world's destitute.