Thieves that rob both their neighbors while they are incapacitated are always satisfied about keeping their ill-gotten gains.
Which land are you actually so pissed off at Poland getting? It all contained Poles. The only two real points of contention are Silesia and Danzig.
In Silesia, the compromise line was about the best that could have been drawn on ethnographic grounds: remember, the original plebiscite was all-or-nothing and took no account of local majorities (which served British economic interests), whereas German local majorities in Posen and West Prussia had been handed over to Germany. Sure, no partition can be done according to proper democratic principles in the middle of a low-key war, but both sides were equally to blame for that.
As for Danzig, well, since Germany waged trade war on Poland, the argument that it needed sea access is pretty much vindicated, meaning autonomy rather than Polishness was the fair option; the Poles rather undermined their own argument here by building Gdynia, but then, Beck was willing to contemplate Germany getting back Danzig in some circumstances, and a sane regime probably would have, eventually.
Everywhere else, Germans are a minority. Local majorities in urban centres surrounded by Polish countryside were common, but in the obviously very agrarian society outside Silesia, that meant strong Polish majorities. That Poland's minority rights were abbysmal is a seperate issue from the self-determination of its territories.
Indeed. So was Prussia and Germany through all the 19th century. No, wait. They kept attacking their neighbours.
Bah. This is one of my least historical trends: extending one's grievances form the age of total wars and absolute ideologies into the pragmatic and cynical international politics of the 19th C.
Prussia was not any more aggressive than any other European state in the 19th C. It was just better at knowing when, why, and how to be aggressive. Wars for which Prussia's opponents in every case bears part of the blame (Schleswig, 1866, 1870) are used as proof of "German aggression". We forget that everybody waged aggressive wars at this point, they just didn't win.
And that's keeping it in Europe. Britain and France liked to go around kicking people's nadgers in and shovelling opium down their throat at the time: obviously the reason the Prussians weren't up to that was because they lacked the capability, since Germany joined the colonial game with murderous enthusiasm later on, but it bears pointing out in discussions of who was "aggressive" in the 19th.
I don't really agree with the way the very opinionated partitions of Poland are usually presented either, to be honest. It was a cynical act of 18th realpolitik. Other changes of hands (to give a nicely illustrative example, France and Alsace-Lorraine) were just as cynical, aggressive, and undemocratic in almost every respect, but they've been allowed to stand.
Prussia stole land from Poland. Then, Poland had conquered east Slav land earlier. Everybody was constantly stealing and conquering for most of history, so if we bring up 18th century grievances we'd be here all day. Soctland's independence was terminated against our wishes by a political clique and a hearty dose of economic blackmail in the same period, I should point out. Am I complaining?
The important thing is how the people of a territory self-determined at the time in which self-determination became possible. Which was in this case obviously 1918, and for Poland.
German opinion was pretty much so: Our slaves not only got free but also dared to take back the land we had honestly stolen from them! Those bastards!
This I'm not going to argue with. Nobody should delude himself that the 19th C was not outrageously prejudiced; in
all quarters. Check British (and American!) remarks about Irishmen, for instance.
Sorry, but I'm sniffing the myth of Evil Agressive Germans Forever.