While I don't disagree in principle, you need to walk many miles in their shoes to see how they got to that point of anger and frustration. Maybe cut them some slack from the start by letting them vent, and them only give them some shit after you've demonstrated significant patience with them & they're still being pissy. Sometimes people in those situations get tired of explaining and/or justifying themselves over and over, so they adopt an acerbic attitude just to push people away so as to avoid having to do it so much.

The world can be incredibly frustrating for those so disadvantaged, and some of them just don't have the mental fortitude to stay positive through it all.