Serious question - when do you think, to within five years - this happened and why?
I'm not a Trump supporter, but I'll take a shot. When I was born, the US represent fifty percent of the world's aggregate GDP. Today it represents about twenty percent. 50 is greater than 20.
It's not that we have diminished, rather other societies have prospered, largely as a result of importing the American ideal.
Greatness should be measured in absolute terms, not relative.
By this standard we are getting greater as a nation all the time, despite the tragedy of Donald Trump's election. "We are getting greater all the time" is not an exciting storyline. It does not promote stories of nostalgia and glory times yonder when we were young. But it is true.
Think
-- Would you really want to live in a country that had never nominated a woman as a major party nominee, ever?
-- Would you really want to live in a country that never completed a successful landing of a first stage rocket, and all space rockets could only be used once?
-- Would you really want to live in a country that never once produced a person who could jump 25,000 feet from an airplane and still survive?
-- Would you really want to live in a country with a lower median income, a lower stock market, a higher poverty rate, a less valuable currency, and a lower GDP?
Hopefully not. All those describe this country a year ago.