I see the point you're trying to make, but this is such a lopsided comparison as to be bizarre. A $10mm house in SF could easily be under 5000 sq ft, while a 120 story residential tower with 25,000 units would easily be one of the biggest and tallest buildings in North America, and would cost billions to develop.

A much better comparison would be a 6 bedroom mansion for $10mm, or a small building with ten 1-bedroom units. And if you look at high end real estate, the per square foot price is often multiples above the median, which is why it's more profitable to build those than lots of small units.