First of all, the Egyptians didn’t use the term ‘pharaoh’ to refer to their ruler. Pharaoh simply means ‘great house;’ probably a reference to the fact the the ruler lived in the greatest house (the palace) in the land, and was first used to describe their ruler by the Greeks.
In the simplest of terms, an Egyptian pharaoh was nothing more than a king and like most ancient cultures, Egypt was ruled by a king, a strong-man who was able to impose order on society.