Not me for sure. If your utmost measure of value in life is GDP, then I feel like we won't understand each other.
Worst part is I can't escape this mindset here, thanks to US billionaires generously bankrolling "NGO's","think tanks" and "independent news outlets"
So we can say, the multiculturalism is not the cause of the wealth. The truth is, the causes of the wealth are the sizeable population, regardless of origin, and the vast natural resources it controls. The US is a westphalian state, run like a business. The European nations once were nation states, but have also adopted this model. It works, if your goal is economic output, and unfortunately your goal must be economic output because otherwise you can't compete militarily with a rival who's goal is economic output and you'll get subsumed.
The "New Colossus" that adorns the Statue of Liberty is a fun little poem, but it does not in any way reflect the actual policies of the United States for much of its early and middle existence. We were a country that was happy to import wealthy people, scientists, conscientious hard workers, etc, while keeping the riffraff out.