The Silicon Valley is definitely a special league. When you look at the exit numbers, nothing compares. Now pretty worried about low level of exits in Europe and in France particularly 
UK still leads the pack in term of number of deals but Sweden is first in term of amount (Spotify effect).
France is 250 times smaller than SV, 10X smaller than UK and 6X smaller than Germany... France seems to be stuck (no exits or very low ones on its soil)
When you look other countries a lot of them have local champions who became global early on (Australia: Atlassian / Sweden: Spotify / Netherland: Adyen...)
To be self-sustainable a tech ecosystem needs Resources X Capital X Exits. If you ask me France is 0.5 (growing number of entrepreneurs but lack of global ambition) X 0.7 (descent capital available at early stage) X 0.1 (no local exits and no bridge with other ecosystems)
France is like the Saccorythus an ancient animal with a large mouth (vibrant ecosystem) but no anus (exits)... which means that the animal must consume its food and excrete it from the same orifice.
Another way to assess an ecosystem is to identify number of world class people X by their desire to create a startup
In Silicon Valley the number of world class people is very high but desire to create your own startup is going down...
In Europe it’s the reverse... Not enough world class entrepreneurs but a strong desire to create startups
Interestingly the most successful European ecosystems are the ones who speak English...
