I think he used pyramid building precisely because it was such an astonishing achievement. Similarly with the space programmes. His point was that accomplishmen

I think he used pyramid building precisely because it was such an astonishing achievement. Similarly with the space programmes. His point was that accomplishment wasn't enough; that innovation requires a transformative effect on people. His examples of innovation all had a multiplicative effect on human labour, knowledge or communication. Pyramid building and space flight were impressive and inspiring but didn't have a lasting effect on how people live their lives.