DUS is not quite the richest, but not doubt economically very strong, and in a massive metropole area (Hamburg is actually the richest in terms of inhabitant's average wealth, whereas FRA has the largest GDP of the big German cities - followed by DUS as the next big one - Berlin can usually be found near the end for any of these and other rankings (
Top 50: Deutschlands Power-Städte - Wirtschaft - Bild.de)