One of the intangible kinds of wealth that "poor" Americans enjoy is societal protection against devestating natural disasters like the earthquake in Pakistan.
One of the most disturbing aspects of Hurricane Katrina, to those of us fortunate enough not to be directly affected, was that our vast national wealth apparently did little to mitigate the damage. However, that's not true at all! Weather satellites and weather prediction are very expensive and very hard to do, and our investment in those technologies gave the residents of the Gulf Coast days of warning time that would have been unthinkable for more primitive societies. Those extra days potentially saved hundreds of thousands of lives.
As for earthquakes, it's unlikely that a 7.6 in California would kill nearly as many people as the quake in Pakistan appears to have killed. I'm no expert, but I'd predict an American death toll of hundreds, not tens of thousands as we're seeing there. Why? Because our structures are built to much higher standards, at much greater cost, than similar buildings in Pakistan. Further, we don't have hills and mountains full of stone age villages just waiting to succumb to mudslides.
Even the poorest Americans enjoy the intangible benefits of our advanced civilization, though the wealth won't show up in their bank accounts or income statements. Another reason why, by any reasonable historical standard, there really are no "poor" Americans.