alt Hacker NewsDACH societies are extremely class based, in fact most of European royal families come from there. They take it as a point of honor to be rude or at least gruff in daily interactions, it's not about you. Their cynicism is indeed a poison, no need for it as the real life will bring enough unexpected challenges.
European royal families have pretty much nothing to do with the modern DACH region, and compared to the UK royal families in continental Europe have very little influence.
But the rest is pretty much true unfortunately, though I wouldn't call the behavior rude because it's not seen as rudeness by people who do it. It's more that being optimistic, feeling surprised by things, expressing strong emotions is all seen as naive and pointless. There is also a strong aversion to taking risks which is pretty frustrating. Even when you can show they are calculated risks.
However not the whole DACH region is the same either, the cultures are pretty different, the only thing in common is really only the language. I had better success in Germany than my own country of Switzerland