There are already 10k people per square mile (incl. forests, recreation areas and water ways that are hard to get rid of without making Berlin completely uninha

There are already 10k people per square mile (incl. forests, recreation areas and water ways that are hard to get rid of without making Berlin completely uninhabitable). Per square mile of settlement area it's 24k people. (state statistics office) Berlin sits right in the middle of a swamp (one explanation for its name is that it's derived from a slavic word for swamp), so there are limitations to how high you can build without things falling over. If at all possible, the manhattan approach of going vertical is at least crazy expensive. There were 8744 new units built in 2014 (state statistics office). There are (according to the article) 40k new residents per year - assuming that on average 2 people share a unit, that's an annual requirement for 20k new units. My guess is that Berlin simply doesn't scale.