Land prices get more expensive than gold itself.
Hong Kong island, is roughly in its natural status, a big rock that emerges from the sea. The existent flat land is usually artificially "created" by reclamation.
Every buildable spot gets easily occupied:
The developers usually utilize the land occupation to its maximum capacity. A little more than just 25 m2 can give space to 80 apartments:
Hong Kong is one of the cities in the world with the highest population density (for reference only: 247,501 people per square mile - 20 times higher than India's).
In 1998, with the move of the old Hong Kong Airport from the Kowloon Peninsula to Check Lap Kok, the building height restriction was relaxed, from 20 to >80 floors.
Today, aiming as usual to utilize the land, there are residential buildings being built with 80 floors or more, giving the impression that the 20 floor-buildings nearby are just tiny little house.

An excellent book by Tiziano Terzani that takes you into a trip around a spiritual dimension of South-East Asia!
Francesca sits on the front porch with some iced tea, trying to cool herself off. It is a scorcher. She is barefoot, her blouse hanging out of her jeans, her hair fastened up by a tortoise shell comb.
"-- going over and over in my mind every detail, every moment of our time together and I ask myself, "What happened to me in Madison County?" I struggle to put it together in a way that allows me to continue knowing we're on separate roads. But then I look through the lens of my camera, and you're there. I start to write an article and I find myself writing it to you. It's clear to me now we have been moving towards each other, towards those four days, all our lives -–"