I fundamentally disagree with your assessment that the economy is extremely healthy.
The top 1% holds more wealth than the entire middle class, 29% to 21%. The top 20% hold 77% while the bottom 20% hold just 2%. The worst income inequality since the roaring twenties. The American Dream is one of the middle class, not the uber wealthy. We can accomplish all the goals you mention, clean energy(GND), universal healthcare(like every other first world country), public higher education, reparations, immigration reform, by restructuring the economy so that it works for all Americans. Not just the privileged few.
We're founded on the ideals of the Enlightenment. Life, Liberty and the pursuit of Happiness. Liberty and justice for all. All men are created equal. You know the words; all that secular humanist razzle dazzle. That's what makes our country great, not crony capitalist robber barons. America is the lone superpower in the world because of the middle class we created with progressive politics that allowed everyone to succeed, from Lincoln freeing the slaves to Teddy busting up the trusts to FDR's New Deal. It's the elites who hoard wealth for its own sake who have completely changed this country with voodoo Reaganomics over the last few decades. I want to restore America to its principles and allow it to fulfill its full potential because I believe in that potential. Not just jump ship because another country has a good idea. We are the great melting pot, we'll take that good idea, the person who had it, their cousin Susie, and the hummus they were snacking on.