I don't like the part where Elon Musk is saying that "isn't it a shame" that the Egyptians' pyramids and the Romans' aqueducts were highlights of science and engineering, and that the skills to create them atrophied or were forgotten.

I'm kind of glad that we don't do things like trying to replicate the glory of the pyramids if it's true that they required masses upon masses of slave labor to build them. Similarly for the aqueducts (I don't know if slave labor was used to build them, and a Wikipedia search didn't yield anything useful).