Anyone who acknowledges that Europe prospered from pillaging during the colonial era is also forced to see the question of how they managed to stay on top in the conquering game as long as they did.
If on one hand their imperiaist success was by unearned random chance, then morally it puts them in the same stratum as all the other non-western empires that tried to conquer as much as they could when they got the chance.
If, on the other hand, you say there was some exceptional property that granted them their unusually great success, Industrialization is the most obvious answer, which in turn raises a second-guess about how much they really stole, and how much they actually produced.
Outside of these two options, you can't really characterize the west as an exceptional evil without also invoking something like "European magic," which is poopy.