Personal anecdata:
I'm Canadian. I have two degrees from UWaterloo (CS & Math), have been on the founding team of three major exits (one "unicorn"), and have a Harvard MBA. I've lived in the US, mostly under TN status, for fifteen years. (Unlike H1-B, TN status is not dual-intent, and does not allow immigration.)
I'm starting a new company now in Canada. Labor-intensive, probably creating a few hundred good jobs in the first year. I'd prefer to start it in the US, preferably Nevada, but have no acceptable way to legally do so.
This was frustrating for a while, but I'm over it. Europe & Asia are operationally more complex to serve, but that's less overhead than immigration. And I've learned the rest of the world has just as much opportunity (and probably more available investment!) than the US.
I'm just one person, but I've seen this play out five or six times among my peer group alone. If you're a non-citizen entrepreneur with valley/NYC connections or US startup experience, I strongly recommend taking that knowledge and competing in the bigger global pool.
As the global economy flattens, the odds are growing every year that the next megacorp in the US market won't be American. The government should be fighting that trend, not doing everything in its power to accelerate it.
edit: "no legal way" => "no acceptable legal way". Anything is possible.