- Good, technical education system. There might be no worthwile IT classes in school, but its very easy to get into a computer science course in university.
- Relatively wealty country, so programmers can work on their personal projects and not worry how to pay rent.
- Big IT industry, which helps both with education and paying rent.
- Maybe more free time compared to other countries?
- And Germany simply has a high population, the second biggest in Europe after Russia.