"Contractor's profit," is the very loose term they use

.
This is how they can buy 1/4 acre plot in Runda for 30m, build a 6 bedroom palatial manse on it for 20m, and sell it to the public at 150m where at that "cheap" price it will go like hotcakes.
Moral of the story; become a contractor post haste
In the final analysis, it all boils down to sheer plain old hard work and dogged persistence. Nothing more, nothing less!!