Egyptians used build huge constuction for the pharaohs' tumulation for at least 1500 years, first as mastabas then as pyramids. Then they stopped building them, and opted to underground mausoleums as the ones in the King's Valley. I can imagine the main reason for this is that the former were more difficult and costly to build, but is it the main reason? Or is there another other cause for such a difference between the two time periods?
There's always more to be said on the topic, but I wrote about this in Why was there such a long period without the construction of pyramids in ancient Egypt? Khendjers reign was around 1760BC and and the next pyramid wasn't erected until 721BC by Piye?