> Saudi Arabia has this weird affinity for these completely ridiculous sci-fi projects

Same reason Egypt is building a decadent new capital: it lets the ruler pay off his supporters.

Bingo. The boondoggle is meant as a cover for naked cash transfer. It's a thinly veiled excuse and it's meant to fail. Maintaining it doesn't generate the cash transfers of the desired magnitude

Also most "normal" people will be physical separated from the ruling people. Makes it harder to protest government buildings.

That benefit only manifests if the line city is built, which obviously it won't be.

No I mean in the case of Egypt.

I guess it does get them attention