Exactly. Was it rational to build the pyramids? I reckon to the slaves it was a moot point.
Poul Anderson has a novel called “the High Crusade” where the alien conquerors descend on medieval britan and get their spaceship siezed by the completely savage knights when they charge it.
Freegards
More modern evidence has shown that the great pyramids were built by a paid labor force. One of the things they paid them in, was beer.