I will respectfully disagree with parts of it. Please, consider this: It's because Europe was already rich in the first place, that it was able to colonise Africa.
Colonial endeavours were megalomaniac and audacious projects of rich countries that made no economic sense (like all government programs!). This is why the "pragmatic Germans", unlike the British and the French, were never enthusiastic about it.
I think basic things like freedom, respect of property rights etc, that were never a reality in Africa, can better explain the wealth gap between the continents, and this is why bitcoin is so important, because it will bring freedom, property rights etc, and therefore, true and long-lasting development.
When looking at the atrocities committed by colonial powers, it's important to add some context. Africa was almost never a peaceful continent. It was true before, during colonial times, and also today.
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