Definitely for Elon Musk, but for Einstein I think being a German Jew as Nazism rose and terrorized Jews all over Europe naturally led Einstein to go to the US. The US was not actually all that welcoming. Due to racism many European top performing Jewish scientists ended up teaching at black colleges.

But regardless of the challenges he faced it beat staying in Europe and watching the Nazi war machine steam roll one country after the other. Lots of countries restricted access to Jews. Britain, US, Palestine etc Jews just had to go wherever they could get in.