Mainland Europe is a big place. (As is the United States, Japan, etc). There are huge, huge, huge disparities in income between e.g. programmers working finance in Paris and somebody cranking out back office code in Poland.

I have no specific knowledge about the market in Vienna, but find it easily within the realm of plausibility. You'll still be making a 50% premium to e.g. some fairly senior developers in the Midwest, and almost a 100% premium to common programming wages in Nagoya.