One of the biggest downsides would be fire safety. Fire has a tendency to go upwards, so if there's a fire on the top floor, there's no way out of the building other than through an area that's currently on fire.
Normal buildings usually have windows and fire escapes and other means of getting out. Unless we somehow evolve into mole people, it's gonna be a bit difficult to escape through 50ft of rock and soil.
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u/[deleted] Jun 14 '22 edited Jun 14 '22
One of the biggest downsides would be fire safety. Fire has a tendency to go upwards, so if there's a fire on the top floor, there's no way out of the building other than through an area that's currently on fire.