I think most folks define "rich" as "making far more money that I am". In general most people tend to think of themselves as being in the middle class. It isn't uncommon for people in the top quartile or even top decile to see themselves as 'upper middle class' or even just middle class in general.
Here in California median household income is a little under 60k, the top quartile starts at a little over 100k, and almost 6% of the population makes over 200k.
Nationally, median income is about 50k, the top quartile starts a little under 100k, and a little less than 5% of the population makes over 200k.
As far as politicians go,
in the campaign President Obama defined rich as being in the top 3-4% of incomes, or over about 250k a year. I pretty much agree with that assessment. I do however agree that the cost of living should also be factored into tax rates (which it is to some extent through deductions) as some places are more expensive to live in than others.
I think in general, those who make more are not only better able to contribute more to the upkeep of society, but also benefit more from it. Lack of crime, presence of roads, an educated populous, and so on are all highly conductive for the generation of both individual wealth and the common good. If you depended on the free market to provide these things many of them would go ignored hoping that someone else would foot the bill.
