[dragonwriter]

> They can solve desirability by building together that stuff that makes a city desirable - other people, businesses, walkability, modern design.

The things that make a city desirable (and supportable) are largely natural features of its location, which you either can't currently practically engineer (pleasant weather) or which are very expensive to engineer (like access to fresh water supply). Places that are currently unpopulated and have low land prices are usually lacking these things.

[mch82]

How come people continue to live in flood planes, hurricane zones, or the Northeast?

Massive Winter Storm Hits Northeast - https://www.npr.org/sections/thetwo-way/2018/01/04/575643483...

[dragonwriter]

> How come people continue to live in flood planes, hurricane zones, or the Northeast?

Because those places have desirable geographical features, like access to fresh water (flood plains tend to have this in spades), access to arable land (doesn't always support high density, but supports at least people to farm and support farming, because people living elsewhere need to eat), access to natural features that are convenient in trade (like navigable waterways and natural harbors), access to valuable natural resources, etc.