You are not reading the context correctly. The original point was that establishing colonies was very risky, to which whyever implied that colonialism was not a success story. But in fact it was extremely successful from a risk analysis point of view. Some nations chose to risk lives and it paid off quite well for them. The nuance of how the natives were treated is frankly irrelevant to this analysis, because we're asking "did the risk pay off", not "did they do anything wrong".