Why did humans decide to settle down in very harsh environments like Siberia or the Saharan Desert, why not live in places more moderate and more accepting to life and civilization?

Question

Why did humans decide to settle down in very harsh environments like Siberia or the Saharan Desert, why not live in places more moderate and more accepting to life and civilization?

In: 2272

Answer 1

Very likely, because someone else was already living in the nice spots.

Or, just as likely, some other group drove them from the nice spots.

Human history is full of migrations, invasions, etc.