Do you have a source for this? I have long speculated that the pyramids were a massive make-work program, I just never bought the idea that there were just tons of slaves doing that work. Obviously Ancient Egypt was a slave society, but where did all of the slaves come from? If Egyptians like enslaved an army or like another city that was so massive that they needed to find extra work for them, building megalithic structures, etc., how do they make sure the slaves don’t revolt? They would need many more slave masters, more slave catchers, etc., and where do those people come from? The political economy of Pyramids being built by slaves doesn’t add up. They must have been excess labor. I’m no expert but the back of the napkin math always seemed really fishy to me.

Edit: oh I see the "fall of civilizations recommendation further down, I’ll check it out