Well, Jacob duped Esau for his father's blessing and God still Blessed Jacob with bountiful cultivation of land when he worked. If the person is Blessed by God then they can cultivate the dessert even…
To say the land of where Israel is Blessed currently sounds odd to me. It's the People that God would Bless, that would bring fruit out of that Land. If you watch any tourist video from Israel, there is literal shit feces and garbage all throughout the streets. They didn't make anything out of that land.
Abraham could go to Canaan, Egypt, always got Blessed, even when he technically lied (about his Wife being his sister so people would be less likely to kill him over her).
I think God left Cain to live because Cain gave God some Wisdom over His Creation - not to openly favor one sibling over another directly to their face because it causes animosity amongst them and trouble in the family. Cain still got a bad punishment though, had to leave his Homeland and was a perpetual Wanderer.