You don't seem to realize how different world trade was before the end of WWII. Before the end of WWII, a nation needed a navy (and probably colonies) to import significant amounts of raw materials or to export significant amounts of manufactured goods. During the 19th Century and the first 45 years of the 20th Century, Germany was prohibited from trading with the colonies of any nation with a navy because a nation with a navy used it to make war on any manufacturing nation who dared trade with its colonies.
Germany never got any real economic value out of its colonies. The logic that led them to go after them wasn’t fundamentally economic, it was about more nebulous things like national prestige. The Germans felt slighted by the fact that Europe’s other powers had colonies and they did not. The German foreign minister von Bülow expressed this plainly in a famous statement he made in 1897: “Wir wollen niemand in den Schatten stellen, aber wir verlangen auch unseren Platz an der Sonne.” (“We wish to throw no one into the shade, but we also want our own place in the sun.”)
Germany didn’t need battleships and colonies; she wanted them, because they were how Great Powers measured themselves in those days.
In 1914 Germany had the largest and fastest-growing economy in Europe. They produced twice as much steel as Britain; 63% of their exports were finished goods (see https://www.britannica.com/place/Germany/The-economy-1890-19...). All this prosperity came from the industrialization of continental Germany, not from their few tiny colonies. And all Wilhelm’s navy ended up accomplishing was soaking up absolutely mind-boggling amounts of money and making more enemies than even Germany could afford to fight.
