Anyone can prop their GDP by borrowing and making their children under debt. Also, anyone can get rich by looting their neighbors. That's exactly what happened in colonial times. And former is underway. So not sure what you are on about?
How do you explain the fact that many European countries who had marginal or no colonial empires are among the richest countries in the world today? (Germany, Sweden, etc.)
That's easy. Concentration of looted wealth in a region and regional internal trade with barriers for external entities. Why do you think there are so many voices against WTO? It challenges the status quo built by force.
Most wealth in most European nations depends on local production and expertise.
Why is e.g. the Norwegian fisherman richer than the Bangladeshi fisherman? It is not because he gets more money for each fish he sells.
It is because the usage of modern fishing vessels and technology allows him to fish a lot more fish. In Norway we tried to give Bangladeshi fishermen modern Norwegian fishing vessels in the 70s. If failed because they do not have the skill and infrastructure to maintain and support a modern fishing fleet.
Value lies in better both superior equipment and the knowledge of how to use it effectively. That advantage exists in Europe regardless of whether Europe gets to exploit other nations or not.
Even in colonial times, most economic activity happened locally. Tobacco, sugar and spice does not grow the core of the economy. What mattered most was intensified farming locally. The usage inanimate power, labor specialization and cheaper transport to increase production of food, clothes, tools, furniture, housing etc.
Even without actually exploiting the colonies Europeans would have benefited hugely from the maritime explorations. New crops such as potatoes benefited European agriculture greatly.
