Bounties attract serious brainpower to the challenge.
The idea is to green a dry area, make it more livable, provide jobs to local people, boost tourism and make money flipping real estate.
This idea would make sense for entrepreneurial people living in drought-stricken areas such as rocky Mediterranean islands, Canary Islands, outskirts of deserts, and similar.
Stage 1 - Build a horse ranch
In a dry land where conditions are unfavorable for livestock and nobody has ever seen a horse, build a horse ranch. Make it big, beautiful, and capable of providing good care to as many horses as your land area and budget allows. All the hey/feed will continuously have to be imported because there are no pastures in the area.
You could keep a few horses of your own and offer the remaining capacities to other local people who would like to have a pet horse and can afford all the expenses (rent, food, care, etc.)
The ranch could provide tourists with horseback tours of the area.
Stage 2 - Buy cheap, dry land
Buy cheap land in an amazing, but dry, semi-desert location. Possibly with a view. Somewhere that tourists like to visit.
Design beautiful plots and chalets.
What will make your plots different from the rest of the area, higher-priced, and easy to sell? They will be immersed in an oasis.
Stage 3 - make a frikin oasis!
design an irrigation system
cover the infertile ground with a thick layer of horse manure
protect the manure and plants from wind erosion with rock walls
if necessary, cover the manure with biodegradable coconut erosion control blankets to keep it in place while the plants take over
select resilient plant species that will be able to survive in the area when they are big enough
take good care of them and immerse your chalets in greenery
keep expanding the oasis as the horses produce more manure
With some luck, the ranch operations could be sustained via the horseback tours. Otherwise, the investment would be paid for by renting or selling the chalets. The real value though comes in the form of a more livable ecosystem. The greenery would boost tourism, improve the economic prosperity and the general wellbeing of people living in the area.
If it works as envisioned, buy more adjacent land and continue to expand the greenery. Make your area amazing.