The British Empire was lame

Did the British Empire ever stop to think and take a look at themselves in the mirror and ask themselves the questions, (1); If we as a people of Britain capture, ship, train, and enslave people from a continent that did not belong to us, will there be any catastrophic and destructive consequences done to our people given enough time displacement, and will these negative consequences be at the magnitude that our people will be either completely taken over by another land or do we think that we (Britain) can surely get away with committing crimes against humanity for so many decades. The poor excuse that Great Britain told themselves, (for the justification of their evil actions against the African people), is this: "We are civilized and we owe it to the entire world to show the world the methods of how to be civilized." This is the lamest excuse that a nation can tell themselves that gave them the conscious to just simply take over, kill, and build railways, schools, universities, hospitals, governments, libraries, roads, rural and urban communities.