That’s a good geometry for quake resistance, but even the Great Pyramid suffered from a major quake during construction. The corbels at the top of the Grand Gallery were found (in modern times) to be hanging on by a fraction of the inch on one end. It’s probably the quake that led to the settling that cracked the structure sufficiently that the ancient inspection passage was dug out above the King’s Chamber.
The Great Pyramid is an equilateral pyramid, but a building 2km high would have to be a more flattened type pyramid to transfer all that weight to the bedrock similar to what the ‘flying buttresses’ did for the medieval cathedrals of Europe........................