Colonization has made Brits more dumber and backward as a nation
Once colonies were conquered and at no cost could be looted of their resources. There was no motivation or necessity to improve or develop the nation in terms of science or other advancements.
This is the reason why UK has no achievements like industrial revolution in last century unlike Americans who took the world to nuclear age and Soviets who took the world to space age
This is similar to the fate of other colonial empires like Spain and Portugal who after looting all the gold from Americas simply never had a need to develop and advance in science or industry
They simply could buy anything they wanted with the gold and never had the need to manufacture them.
Once gold ran out both became poorest economies of Western Europe in the present
This is why Spain and Portugal are part of PIGS economies and UK seems to be on the way to join them.
PIGS (economics)