The US gained a lot of highly qualified immigration around WWII, when Europe tore itself into shreds. Poles, Italians, Russians, Germans, you name it.
And it is hard to disrupt the advantage of places like California ever since. Once you have top universities and top corporations somewhere, individuals will flock to them instead of trying to create competing hubs elsewhere. Plus the dominance of the English language all but guarantees that English-speaking countries will be the net benefactors of this global movement.
For all their advantages, Germany, Japan et al. still struggle with their parochiality when attracting foreign talent, while the US can do this really, really well. Take the entire roster of top IT people in the US and make a checkmark next to every immigrant or a child of immigrants. Similar lists in Munich, Paris, Tokyo etc. would look very different. Most European countries struggle with the fact that recent immigrants tend to be overrepresented in prisons.