Honestly, if the US had generally a welcoming visa/immigrant policy, I and most startup founders would not even think to set up my company elsewhere as it is in some regards "the center of the world". But as the US gets a more and more unwelcoming image, other places like London, Berlin or Vancouver rise. Of course tech in the USA is not dead and will not be any time soon. But it could be attracting much more talent if it was more open and easier to get into. Look at Dubai: you want to found a company in Internet Zone? Go there, found the company, get your visas in a simple process, move over. The fees are high, but it is straight forward. That is how it should be in the US. I know there are investor visas, but it is a difficult process with an open end. And then there is stuff like the random travel ban, which, for example, makes it impossible to take my wife (Iranian) with me.