This being the only part worth responding to, how in the world do you try to lump in the creation of the internet as part of the sunk cost of SpaceX's rockets?
Because that is where he got his money from
And until SLS has a second launch proving otherwise, you're right.
But you don't even want it to get that first flight.
That's like me challenging you to a fifty yard dash, but let me tie you up first.
SLS can fly as often as shuttle--and once flying, should be able to fly with less problems because there is no orbiter. The problem is that NASA needs a larger budget
Webb is worth several SLS cores by itself--and Curiosity is also in the billions. Golden Spike is the billions. There is just no cheap way to do this.