There are many ways of looking at it. Here's an excerpt from Carola Barton's summary of some of the ways of viewing it:
We sometimes treat it as a matter of blame: the poor are poor because they cannot or choose not to be better off. We sometimes treat it as a matter of virtue: people choose material poverty because it generates—or does not interfere with—spiritual well-being.
We have a long history of explanations for the existence of poverty:
Sociology: the poor are poor because human beings instinctively look to differentiate themselves from one another, and someone needs to be at the bottom of the pyramid
Economics: the poor are poor because economic forces depend on a mass of impoverished workers to provide the labor that makes our societies run
Psychology/Physiology: the poor are poor because individuals have unequal faculties, and in a society that does not compensate for those inequalities, someone must wind up at the bottom
Scarcity: the poor are poor because there aren’t enough resources to go around
Environment: the poor are poor because of regional environmental conditions—climate, topography, soil, etc.
Spirituality: the poor have chosen material poverty because they have found, or have been endowed with, immaterial sources of wealth