Are you sure that's not caused by something else, like having a single language used by more than 300 million people, instead of 24 official languages [1], each used by, at most, tens of millions?
There are huge variations in the number of tech unicorns across Europe, uncorrelated to population size. See Sweden or Netherlands. Not saying it isn’t an advantage, but other factors are much more important.
[1] https://en.wikipedia.org/wiki/Languages_of_the_European_Unio...