Idleness refers to the state of being idle, inactive etc when it comes to economic prosperity and growth idleness is one thing that fights against it from the times of old till now any individual or even country that has had economic power is one that was not idle but always active engaging in one activity or the other that will be helpful to the economic growth of that person or country
Basically being idle doesn't guarantee one's success or achievement very correct but mind you it's not the greatest problem to economic growth or prosperity, there are so many factors that has limited an economic growth but not necessarily being inactive cause from a wide range of knowledge there's no country that's being idle or inactive in one way or the other, they all are striving to make their country better so I think when you talk about idleness you should be channelling it to personal self, cause most individuals find themselves in this state making them unable to catch up with alot of task and responsibilities.