Ancient people were smart, they had good math and good engineers, they built things. We won't really know and we can't go back and just ask them why. We know they had some precise engineering and construction skills and tools, heck some of them even built actual batteries inside clay jars much like modern lead-acid batteries, albeit quite low in power output but they had a concept of electricity. I don't find anything conclusive to say that the Pyramids of Giza were ever a wireless alternating-current limitless electricity generator powered by a hydroelectric plant from the Nile. Now, can we leave the dead guys in the ground where they belong, let them sleep in peace...