[dukeyukey]

1. Europe isn't a single tech market, it's dozens. You might get paid California wages in Switzerland, Midwest salaries in London, and less elsewhere.

2. It's also dozens of markets when selling products. As much as the EU tries, functionally there are still barriers to trade across the EU, let alone places like the UK. Stuff like language, culture, religious practices all impede easy scalability, not to mention differing laws.

3. The US is a continental-scale superstate mercifully isolated from most of the world's wars. Europe is not. It's that much harder to grow the amount of capital North America sees when the continent is split of more than often at war with itself.