There must be myriad unintended consequences that would come with dumping a whole bunch of water into a desert though? It feels like there's an awful lot of hubris in thinking we could accurately predict all the changes that would cause and know it would have a net positive outcome.
If the Sahara wasn't dry, what would be the knock on effects of losing the dust from it that lands in South America?
If there are, we should have figured them out by now, since that is the story of California during the 1840s. People redirected a bunch of water to turn the desert into a treasure. Kinda literally, since shortly after they found gold, which destroyed all the positive economic change that was brought.
Or take the Netherlands, that used to be a lot of water and now it is a lot of flat land.