Saudi Arabia Wants to Build a City in the Ocean

Im an engineering student, let me answer some questions.
“Why dont they build in the sand”
Because the Red Sea and Suez Canal are huge shipping lanes

“Why in the ocean?”
No need for trucks and cranes, simply have a ship pass into a building and be loaded in moments before going on its way

“Is this a city?”
No, its supposed to be a futuristic port/industrial complex

“Will this impact marine life!”
The project is designed to float on the water with minimal effect on the marine environment.

“What about tsunamis? Earthquakes, meteorites, or other natural disasters?”
Natural disasters are very minor and rare in that area, and the project is designed with sustainability in mind.

“Why not use the money to improve existing city infrastructure in the rest of the country?”
They are, the benefit of being a rich country is you can do both at the same time.
Jeddah has multiple projects to improve it (Jeddah Downtown, New Historical District etc.)
Riyadh has many projects too (Riyadh Sports District, Green Riyadh, KSP, KAFD, Murabaa)