We say that a blanket or jacket "is warm", even though all it's doing is trapping heat that we produce. We say a task "is difficult", even though we are the ones who are having the difficulty in completing it. We say an apple "is red" even if we know that the color we perceive is a property of how light interacts with the apple's matter.
And we often say that people "are poor" rather than "in poverty."
Language exists somewhere between representing the way we think, and affecting the way we think. Attributing poverty to an inherent property of a particular person, rather than their context, seems in line with how we speak (and perhaps think) about a lot of the world around us.
I think this is one reason it is so hard to fix social problems: because the first step must be a critical mass of people who can and will overcome a default way of thinking about the world.