* Gold dropped 1.9% on Thursday as rising economic expectations and inflation concerns vaulted benchmark U.S. Treasury yields to their highest since the pandemic began, helping lift the dollar. * Federal Reserve policymakers are shrugging off the surge in longer-term U.S. government bond yields as a sign of growing optimism about the economy, which could pick up steam as more people are vaccinated against COVID-19. * Robust fiscal support and vaccinations could lead the United States to its strongest growth in decades, New York Fed President John Williams said on Thursday.