[teahat]

Some other contributing factors: cultural attitudes to failure, and as a consequence cultural attitudes toward entrepreneurs, heterogeneous audiences (the USA has ~300M people speaking mostly the same language), far less advanced ecosystem - success breeds success in terms of both experienced founders, broader angel investment, stronger networks etc.

Of these, I suspect the cultural attitude toward failure is by far the most significant. I think the USA breeds more successful startups primarily because it breeds more startups, due to failure being viewed much less negatively.

[nicoschuele]

Point taken. But see, here in Switzerland, even before speaking of attitude towards failure, the simple fact of saying you are working on building a web startup... ...gets you considered as an unemployed failure. That is one major cultural difference.