Wealth that you generate yourself isn't a benefit that comes from society, so social justice doesn't demand it be redistributed. There plainly are benefits that

Wealth that you generate yourself isn't a benefit that comes from society, so social justice doesn't demand it be redistributed. There plainly are benefits that society gives us that give us a chance at generating that wealth, though, as can be seen by, for instance, the lack of Botswanan Web 2.0 startups. Even if you were correct that social justice is radically redistributive of all wealth, however, that would not imply that the $1/day idea is supposed to serve as a positive example. Rather, it shows how unpleasant it is to do so. If they wanted to show equality of income wasn't such a bad idea, they might have done the live-on-$22-per-day project.