Congrats on getting your green-card Swizec!
I wouldn't generalize to Europe here. I think it's a common mistake that I often make myself is to compare the US to Europe as if both were homogenous. San Francisco is different from Detroit, and Germany is different from Poland both economically and regarding people's mindset.
I've moved from Switzerland to NYC on an E-2 visa. I've worked multiple years for both a Swiss and a German startup and have been in contact with Swiss and German founders through an accelerator. I've never heard any founder or software engineer say that taxes, administration, or other people kept them from reaching for the stars. I've also learned that taxes in NYC are easily as high as in Germany and that paperwork in the US is just as burdensome as everywhere else I've had to do it.
I think the reason that so many ambitious people are drawn to Silicon Valley and NYC is that they know it's a place where other ambitious people are. That's precisely why I came, and it's a self-fulfilling prophecy. And I went despite the high taxes (easily 3x of what I paid in Switzerland), higher rent, and burdensome immigration process because I want to be in this environment.
You allude to the fact that people are what matters, but I feel that a lot of the discussion about what makes a good startup ecosystem is about money, taxes, and other administrative side-shows. Those only matter if you have the right atmosphere to start with, and I think we should talk about this more. Especially now that most of us are working remotely and physical location will become less critical.