ne'er-do-well
A lazy, unreliable person who never does anything useful.
A ne'er-do-well is a person who consistently fails to accomplish anything worthwhile or useful, often because they lack ambition or refuse to work hard.
If your town has someone who's always talking about big plans but never follows through, who borrows money but never pays it back, or who drifts from one failed scheme to another, people might call them a ne'er-do-well. The word describes someone who doesn't really try, who makes poor choices repeatedly, or who won't take responsibility for improving their situation. The pattern comes from their choices and behavior, not from simple misfortune.
You might encounter ne'er-do-wells as characters in stories, often appearing as the unreliable uncle, the lazy son who won't leave home, or the smooth-talking drifter who shows up in town with empty promises. In The Adventures of Tom Sawyer, Tom's friend Huckleberry Finn is considered a ne'er-do-well by the respectable townspeople because he lives without rules or responsibilities, though readers discover he has more good qualities than his reputation suggests.
The term carries a tone of disappointment or mild contempt, as if the person could do better but simply won't. It's an old-fashioned word you're more likely to read in classic books than hear in everyday conversation.