Then you have multiplied your launch risk by the number of launches it would take to get it up there, plus there is the difficulty of assembling it in orbit. T

Then you have multiplied your launch risk by the number of launches it would take to get it up there, plus there is the difficulty of assembling it in orbit. The only other project built like that was the ISS, and it took decades and a launch vehicle that no longer flies. The biggest problem would be that it would be in the ISS orbit, which would require a lot of delta-V to get it to its final orbit.