Personal finance guru Dave Ramsey has a lot to say about the nearly half of young adults who are still living at home—a level that hasn’t been this high since the Great Depression. This cohort (those ages 18 to 29) is driving the growth for luxury goods in the U.S., say Morgan Stanley analysts in a December report. The analysis found that living at home freed up older Gen Z’s and younger millennials’ discretionary spending, enabling them to snap up designer handbags and watches. Ramsey, a...