The US might be the best place to start a world-conquering multinational like Google or Facebook, but it's not the best place to live for general social mobility or for starting a small business. Small business startups play a lesser role in our economy than other Western European countries. (https://www.theatlantic.com/business/archive/2012/10/think-w...)
This is provably false. It is incredibly hard to create a small business in western Europe. Capital borrowing is difficult, employee staffing is onerous, and local officials make sure that larger established companies compete more strongly in their areas.
That Atlantic article is both antiquated, and cherry picks data just after the 2008 crisis.
The entrepreneurship rate has been declining in the US for the past few decades. (https://www.washingtonpost.com/news/on-small-business/wp/201..., https://www.inc.com/magazine/201505/leigh-buchanan/the-vanis...)