It is the heart of archaeology for obvious reasons but culturally it has amounted to an obsession unexplained. Roman/Greek is part of western tradition but Ancient Egypt is older and far away from anything we can understand about ourselves at least without deep study. Yet pop culture it has captivated many children's imaginations even though there are many other ancient civilizations. And this began during the Napoleonic wars, at a time of age of enlightenment and splitting away from Christianity. Ancient Egypt plays a grand role in the bible, where it is mainly a villain or a metaphysical kingdom. Is there some deep void in western culture that Ancient Egypt fills with all its Gods and esoteric rituals? The obsession goes so far as to be a cultural appropriation by both whites and blacks.
Largely because Egypt is considered one of the few primary civilizations in the history of humankind.
A few sources on the sociological/anthropological phenomenon of state formation should prove helpful:
Elman R. Service, Origins of the State and Civilization
Norman Yoffee, Myths of the Archaic State
B. E. Shafer, ed., Religion in Ancient Egypt: Gods, Myths, and Personal Practice
So, I would say that it's less of an obsession simply with Egypt. After all, there persists, too, somewhat of an obsession with Mesopotamia (particularly Sumer, but Assyria and Babylon as secondary states to Sumer). Part of it, too, has to do with the unbelievable amount of data we have from Egyptian archaeological finds--these include monumental architecture, textual/epigraphic data, etc. Furthermore, because Egyptian civilization persisted for such a long period of time (even through the Late Bronze age collapse at the beginning of the 12th c. BCE), there is a massive amount of time to study as well. Couple those things with the nature of ancient Egyptian mythology (e.g., the world was created by a masturbating god) and you have a recipe for endless, fascinating avenues for academic inquiry.
Humans also like things alien to our own cultures as well.
Of course, too, this is all not even to mention the early 20th c. British obsession with excavating Egypt (and, subsequently pilfering Egypt of much of its cultural heritage, now on display in the British museum...thankfully some of this stuff is now being repatriated).