Poor people in the US tend to be much better off than many other people in the same country, and those people who are yet still worse off, are rich compared to those living in the bottom 10% of poor countries.
Poor is a relative term, and one that depends on your perspective of income inequality.
The average person vastly underestimates income inequality. Especially in countries like the UK, or in the worst case scenario, the USA, which has the highest inequality gap of all, and in some comparisons require logarithmic scales just so that the USA marker will fit on graph
Just because you are better off and do not need it, does not mean it doesn't affect you at all, it has a HUGE impact upon the society we live in, and there are reams and reams of hard evidence linking these things.
Here is a trust in the UK pushing for greater income equality:
http://www.equalitytrust.org.uk/
Here is evidence they have amassed, fromv arious well regarded data sources:
http://www.equalitytrust.org.uk/why/evidence
They link everything from teenage pregnancy to obesity to income inequality, showing strong correlations, using multiple data sets from various well known and highly regarded sources.
I leave you with this graph:
