Karelis argues that being poor is defined by having to deal with a multitude of problems: One doesn’t have enough money to pay rent or car insurance or credit card bills or day care or sometimes even food. Even if one works hard enough to pay off half of those costs, some fairly imposing ones still remain, which creates a large disincentive to bestir oneself to work at all.

“The core of the problem has not been self-discipline or a lack of opportunity,” Karelis says. “My argument is that the cause of poverty has been poverty.”

http://www.boston.com/bostonglobe/ideas/articles/2008/03/30/the_sting_of_poverty/?page=full