Construction costs generally rise with the height of the building, both due to higher structural demands and because of additional functional (usually also legal) demands - like two elevators and two fire escape stairways for buildings higher than 8-10 stories. Maintenance is also more expensive for higher buildings. Higher buildings also demand larger distances between them to allow light and ventilation. Because of that - except for places with unusually high density like Hong Kong and parts of Manhattan - the sweet spot for high density, construction costs and quality of life might lie in the 5-7 stories range (typical for Paris and Barcelona). Regarding Hong Kong housing situation - in spite of the high level of economic freedom in other areas, the housing market is in a large part state controlled, with waiting lists for buying an apartment.