Welcome to Harry Potter Theory. Today we’re discussing wizarding economics- specifically, why and how a MAGICAL world would still have impoverished people. With the advent of magical capabilities, how can there possibly be witches and wizards living derelict lifestyles? At the very least, shouldn’t every witch / wizard be able to source clean clothes?
In Harry Potter, there are many passages alluding to the lack of economic stability in certain wizarding families- with a particular focus on the Weasley’s. 
From their house to their to their hand-me-down robes, it’s certainly no secret that the Weasley’s were financially stretched. Draco Malfoy even makes a comment towards Ron where he suggests that the Weasley family name is synonymous with this sort of thing.
“Think my name's funny, do you? Well, no need to ask yours. Red hair, and a hand-me-down-robe? You must be a Weasley.”
And when Harry first witnesses the Weasley Family vault, he’s at a loss for words:
“Harry enjoyed the breakneck journey down to the Weasleys’ vault, but felt dreadful, far worse than he had in Knockturn Alley, when it was opened. There was a very small pile of silver Sickles inside, and just one gold Galleon. Mrs.Weasley felt right into the corners before sweeping the whole lot into her bag.”
But the Weasleys weren’t the only characters in the Harry Potter story that were lacking in funds. In fact, in my opinion one of the most EXTREME examples of poverty in Harry Potter is Remus Lupin. It’s reinforced over and over and over that his clothes are tatty and that he looked sickly. 
The first time that we’re introduced to Lupin’s character, he’s described as follows:
“The stranger was wearing an extremely shabby set of wizard’s robes that had been darned in several places. He looked ill and exhausted. Though quite young, his light brown hair was flecked with gray. [...]
“It’s on his case,” she replied, pointing at the luggage rack over the man’s head, where there was a small, battered case held together with a large quantity of neatly knotted string. The name Professor R. J. Lupin was stamped across one corner in peeling letters.”
Then, again at the sorting ceremony:
“Professor Lupin looked particularly shabby next to all the other teachers in their best robes.”
When Harry encounters Lupin for the second time, after their arrival at Hogwarts, the passage even suggests that Lupin had eaten properly for the first time in a while:
“Lupin smiled vaguely and placed his tatty old briefcase on the teacher’s desk. He was as shabby as ever but looked healthier than he had on the train, as though he had had a few square meals.”
Was Lupin SO POOR that he couldn’t afford FOOD? How can this be a reality in Wizarding Society?