Everything you wrote is some definition of hard, but all doable. None of this is purely in the territory of 'known' impossible(like FTL travel).
Now different people have different points where they quit when things get hard.
This is true for even everyday things in life. Quitting triggers exist for people at various points in the ladder. The end of ladder and path both exist, its upto you to decide if you wish to continue climbing, or give up and quit.
Your mileage may vary.
My problem is not the doing thing but the economy of it.
We are nowere near any resource limitation on planet earth for AI Datacenters.
Musk sells this story because he has Starship which needs payload to make financial sense. The payload doesn't exist so he inventes DC in Space.
Its the same thing as SpaceX buying Tesla Cybertrucks.
His old colossus datacenter is a 300MW Datacenter he now rents out to Anthropic because he doesn't even need his own compute. Colossus DC is probably 10x cheaper than his whole Space AI DC Story and will be for a long time.