There's clearly something unique about the US in that nearly half of the capital in the global stock market is US companies, and the gigantic, relatively young, public companies are very disproportionately American (FAANG, etc.) Is it obvious to you what it is, because I've never heard a convincing, succinct explanation.
Here's a illustration of how skewed the world stock markets are by country:
https://amp.businessinsider.com/images/56a627a158c32379008b4...