And no, millionaire or billionaire doesn't matter much. Europe lacks Billionaires not Millionaires. Europe is full of small businesses and by small I mean millions in profits and revenues.
In Europe %99 of the companies are small or medium sized enterprises, which is not different than the USA. In USA however, large companies have slightly higher number of employees which is an indicative of concentration of power and that's how you get your "USA has 5 unicorns in top 10 but EU has only 1" lists.
Contrary to the narrative, Europe has much more small and medium sized enterprises per capita: https://www.nationmaster.com/country-info/stats/Economy/Micr...