More sane policies in the US would be a win/win in my book as a European... Because the US government has a huge influence on our respective government and our lives.

The kids of today grow up to become the leaders of tomorrow. If they grow up with a European worldview and come back to the US, that certainly couldn't be a bad thing.

I didn't think about this effect and probably it would have at least some positives. But I think most US leaders will come from Ivy League universities anyway.