I've been looking at getting a house built, and that starts at about €200k*, but the land in Berlin is at least another €200k on top of that (and usually more).

If I was willing to live in the back end of nowhere, I can get the land for almost nothing, halving the total cost.

But then I'd be living in the back end of nowhere, and turning that into an interesting town (let alone city) would need some very expensive infrastructure to be built, just to support that many residents.

Make the infrastructure cheap, and you can build New Towns.

Most of the developed world seems to struggle with infrastructure during my lifetime, be it major roads, railways, sewage, electricity networks, or anything else.

* list price €100k but that's a cheat as it's the outer shell only, no plumbing or interior plastering