In one way or another, I've addressed the topic of "Where is it like Silicon Valley in Europe" a hundred times, be it in interviews, blog posts, on Twitter or on panels. Nevertheless, there really isn't a "Valley" in Europe, only some places kind of like it. If you want my ideas on that, I have other posts regarding that topic.
Yet, as an entrepreneur in Europe, don't forget that the Valley exists. Measure yourself by "Valley standards" and not just by your peers in Europe. It's been irking me a bit when I speak with start-ups that they compare themselves only to their local competition. So often I hear a pitch and ask who the competition is in the US. Often enough I've heard (unfortunately never directly) "we haven't taken the time to figure that out yet." If this is your take on things, you're nuts. There is most likely some entrepreneur in California who would of swum to the US if possible, worked four jobs for money to launch his venture and wouldn't of thought for one second about "quality of life" nor "spending time with the kids." Think what you like about that entrepreneur's priorities in life but don't forget he'll enjoy crushing you if you're competing against him or her.
The Valley may be sunny and inviting but everyone is there to win. If you don't, you tend to leave quickly. Those who've stayed and continued to start new businesses or finance them have the loftiest of goals. They're probably also not about the money. Sure, they enjoy the perks of an exit but my experience is that lots of people there want to change the world. If not change it, at least try. You hear it in their pitch and you see it in their eyes. Ask me the one thing I see lacking most often when it comes to start-ups in Europe and I'll answer "hunger, drive and lofty goals." The few that have it you recognize immediately. They usually end up succeeding quickly and you chase them to invest in their companies. Those that don't have it probably never will. It's also not about being "American", which also often comes up. The Valley is made up of people from every corner of the earth. Each and every start-up I've visited there was a pot pourri of backgrounds, often Europeans.
So do we need a "Valley" per se in Europe? No, who cares. It's just a term anyway. Do we need entrepreneurs who are hungry, passionate and aiming high? Yes and in order to remain competitive, we need to know who our true competition is in order to know where to aim.