When Qian Zhang boarded a flight from Shanghai to Boston at age 18, she thought she was heading toward the "best version" of her life. It was 2009, during President Barack Obama's first term, when the U.S. economy was rebounding and opportunities for well-educated workers seemed plentiful. She was bound for Dartmouth College, a top choice for many Chinese students, and later found her way to Harvard Business School. Qian embraced the American dream: the promise of equal opportunity, a country that rewards talent and hard work, and a place where global citizens like her could belong. By her early...