You would have a better chance at getting the answer you need if you would give a more precise question. As it is, we cannot be sure as to which colonizers you are talking about. I will assume that you are talking about the colonizers of the Jamestown settlement in what is now Virginia.
The colonizers originally intended to get rich in Virginia by finding things like gold, by trading with the natives, and perhaps by using natives to work for them. All of these three things turned out to be impossible. Seeing this, the Virginia Company had to try a new strategy. Instead of sending out a few gentlemen to make money in the ways mentioned above, they started to try to increase the population of the colony. They decided to try having many more colonists producing things themselves.
In this way, the colonizers of Virginia changed their plans when confronted with the fact that they could not make significant money in the ways they had first intended to.