Comment by credit_guy

SLS is actually very affordable if seen from the correct angle: a know-how preservation program. After the end of the Cold War, the US reduced drastically its military expenditure. The danger was that some day will come (like, you know, the 2020's) when the US will need to restart the missile assembly lines. How do you keep enough people trained at an affordable cost? Well, you keep them busy building a rocket that never launches. Any single launch is money down the drain. You still need to launch, because if you don't you are in danger of fooling yourself: you think you maintained a qualified workforce, but actually they are all impostors. But other than quality assurance, the launches themselves are not important, they are just a cost. So you want to launch as few times as possible.