[acdha]

Definitely, but Kaliningrad had something like 100k people out of a total German population of roughly 80 million? I'm sure plenty of them had grudges but they didn't have an outlet to act on them unless they wanted to sneak through another country on their way to suicidally attack the USSR and, what I think is most important, the alternative was to build a comfortable life in Germany proper, where they were fully integrated with the language, customs, and political system. Grudges don't usually turn into violence, especially with suicidal odds of retaliation, when people have hope. I'm sure there were plenty of old Germans complaining about it – over beers, with full bellies, and going home to warm beds unwilling to do anything which would risk those comforts.

My argument is that Israel needs to figure out how to get to that level for Palestine: if you want peace, you want people to have prosperous farms and businesses to focus their energies on and confidence that if they do so those won't be taken away or destroyed.