I noticed that, too. If one only had the wikipedia article to go on, it would appear that they made way too much money with the covid app for Italy. Which is probably true, but probably not billions?! So, after reading another article[1] (which does not really give strong pointers but leads to) my conclusion would be that they simply somehow became a darling for investors and could finance all these big acquisitions.

[1]https://weeklysiliconvalley.com/bending-spoons-from-humble-b...