"Flipping" usually refers to buying older properties, doing upgrades and renovations, and then re-selling at a higher price. If you built the property new, it wouldn't become a good candidate for flipping until it passes into less-desirable status after some time has passed.

If you're talking about building new homes, what you're describing is pretty much "real estate development," which is a profitable but risky business in the U.S. A real estate developer has to work with local authorities to site the project, which is itself highly politicized and can take years. Then they have to secure capital, hire architects, engineers, builders, and comply with environmental laws. Only once the project is mostly done can they market the homes to potential buyers.