Well, let's see is it possible that these inventors found their own countries so oppressive that they had to come to the US to invent their inventions?
actually fourdc - speaking for inventors from the UK (that includes Scotland, Wales and N Ireland AFAIC) - the main reason why they all go to the US is quite simply cash and the opportunity the US usually provides because of that cash. I can't speak for anywhere else but the UK is notoriously crap at supporting its eccentric inventors - some of whom come up with absolutely blinding ideas. The US is usually quite happy (seemingly) to throw lots of cash at an idea in an attempt to make it work (and if you don't believe me look at the amount of cash that the CIA and military spent on MKULTRA, project Phoenix and project Rainbow - just as examples). I'm not saying that throwing tons of cash at an idea is a bad thing mind you!

To be sure I'm sure some inventors do go to the US because of oppressive regimes back home - just pointing out that not all of them do - sometimes it's merely due to lack of funding in their own countries.

Z