When is the acquisition of personal debt economically wise?

In spite of the large amounts of debt that most Americans have, there are still times when it makes sense to borrow money. If the purpose of borrowing the money is to make a good investment, then there may be a return on that investment that is much higher than the amount that was put into it. For example, suppose a student wants to work at home to make some extra money, but all the work-at-home jobs are done on a computer. If she invests $500 in a basic, functional computer, and then makes $2000 that year doing various tasks online, she has quadrupled her initial investment. And of course, we all know that costs of healthcare in America can be high, so unfortunately, many people avoid going to the doctor. But if, for example, a person has terrible foot pain that is causing him to miss too much work, it may be wise to go to a podiatrist and charge the office visit on a credit card if that person can get enough relief to make walking easier, rather than to risk losing the job!