And then lost the war they've started?
Yes, that's a catastrophe for Arabs, just like losing WW2 was a catastrophe for certain Germans. And also for those in Germany who were exiled from their (sometimes extensive) land, no matter what they thought of the war and its outcome.
Eastern Prussian didn't then go and tried to kill the Western German president when the FRG took them in, though. Besides some whining by a few select bunch, that chapter is closed.
Not so for the Arabs for whom the "Nakba" was and is that the military campaign failed and not that Palestinians now live in misery.