There have been serious speculations by Egyptologists that the massive monuments of the Pharaohs were indeed public works projects. Government welfare on a Biblical scale.

Agriculture on the Nile was driven by the yearly flood. The land was very productive and the population exploded so the government arose as the agency that organized the peasantry to maintain the water control structures needed to manage farming in a rainless desert. The Pharaohs (and their local governors) then warehoused the grain to be doled out between harvests and maintained reserves for times of famine. There must have been times when vast numbers of peasants were just hanging out with nothing to do, a recipe for civil strife; and they were all probably in a pretty foul mood from standing in
line all day waiting for their grain allotment.

The monuments were sort of like our retail economy, an economy based on people making, and then consuming, intrinsically useless stuff.