Already the cataclysm which terminated the Old Kingdom proved that the pyramids, though responding to many of the tasks of a shelter, were inadequate in some respect. The catastrophe during which the Israelites left Egypt was the same which ended the Middle Kingdom. Apparently at that time the futility of the shelters had become known. This implies that during the cataclysm which put an end to the Old Kingdom the pyramids were recognized as potentially fatal traps. The pyramids were not sufficiently protected against electrical discharges.
Lightning is attracted by the vertex of the pyramid.
It seems to me that the ancient way to protect a building from lightning must have been by building thick walls and erecting pillars around the buildings. But this protection could be proven as sufficient only during ordinary thunderstorms. When at the close of the Old Kingdom interplanetary contacts caused tremendous discharges, some of the pyramids became electrocuting chambers. F. Petrie Herodotus I. 124. The Library I. 63.