Higher levels of wealth inequality produce bad economic results in total. Inequality also correlates with higher levels of violent crime, worse health and educational outcomes, and lower socioeconomic mobility, among other problems. And there is a preponderance of evidence to suggest that extreme inequality is incompatible with democracy. Regression studies show that our elected officials are unresponsive to the interests of the middle class (and poor) unless those interests are also supported by the very rich.
The occasional poor person does get wealthy, but there are always outliers. And in some ways that only proves the central point - our economic system is one in which a very few people do fabulously well while many others struggle. Half the wealth in the Fortune 400 is inherited. A person born in the bottom 20% has a 1 in 5 chance of ever cracking the top 50%, let alone making it to the top 20%, 10%, or 1%.
Here is an example of one way people with deep pockets can game the system:
http://www.cepr.net/index.php/blogs/beat-the-press/npr-does-fluff-piece-for-private-equity
Note that it happens at the expense of the taxpayer.
Here is a letter from an investment fund manager describing the 1%, their wealth, and where it comes from:
http://www2.ucsc.edu/whorulesamerica/power/investment_manager.html
Note that he questions whether or not these financial games are adding any value to the economy or simply diverting funds upward.