When Wish is loosing fate in ponykind, she make her wish. She want to see if there is any hope for ponies.

There are different talents. Some of them are useless, but there are talents beyond understanding of common ponies. Some of them requies sacrifice. And when your talent is strange enough, you are seen as dangerous. Wish was pegasus. She was child, brought to her parents as a wish. There is land from the times before founding of Equestria. This land is harsh and cold, but ponies who stayed here survived winter-ghosts, who leaved as three mighty leaders left them.
There are ponies, who are driven by envy and greed, but Wish is different. She wants to live free and without hordes of greedy ponies, who want to pluck every last feather of her wings. Only because they are granting wishes.

But is she really free if she left them in search for Equestria?

Wish is not me. Only my idea.