Private builders. The 5 floor condo gets converted into a 30 floor tower. The residents gets 2x space and the first 10-ish floors. The rest goes to the private

Private builders. The 5 floor condo gets converted into a 30 floor tower. The residents gets 2x space and the first 10-ish floors. The rest goes to the private builder to sell to whoever they want as profits. It often involves demolition of 3-4 buildings into 1 large building. So a lot of wasted space also gets brought into building floorspace.