How might the economy of the 1920s have been different without the advertising industry?

In 1920s, many people were purchasing vehicles, which helped the economy to sky-rocket. Unemployment was at a all time low, which made the 1920's be known as the "Roaring 20's" because almost everyone could get a job.. With a job, you can purchase the things you want, but as people kept buying cars, they realized that they really didn't need to keep buying.