How did the exploitation of the colonies bring huge profits to European countries?

The exploitation of the colonies was very profitable. First, there was no need to pay for resources from the colonies (and these were often such values as gold, diamonds, etc.). Secondly, there were a huge amount of these very resources – a less developed society had not yet had time to develop them. Thirdly, there was no need to spend money on workers’ salaries, on the creation of decent infrastructure. And fourthly, there was no need to spend money on a full-fledged army to pacify the disaffected, because they were practically unarmed.