Every serious accounting of the project says the same: it's batshit insane.
The scale is ridiculously big (170km long, 500m high), the location is ridiculous, the shape is the opposite of what you want in urban design (a straight line means the opposite ends are going to be disconnected, no matter how good your trains are), and every single design element is made to look good on a video presentation before being practical.
Management is reportedly made of oil barons who get violently angry if anyone questions their decisions, and foreign contractors who know the project is doomed but don't want to speak up while the free money is flowing.
It's a huge farce.