How did land speculators make profit?

The land speculator buys land under the belief that he can later re-sell the land at a higher price and make a profit. The speculator would look to see where people are likely to move in the next 5-10 years, so it could be on the outskirts of a small city or untamed wilderness if there is a huge migration in that area and buy the land in advance of the interest from normal people. As a result, he would pay very little for the land. When the land becomes desirable to normal people, he can raise the price and re-sell it.