LONDON (Reuters) -Global investors admit to flying blind in markets roiled by erratic U.S. trade rhetoric and chaotic economic forecasting, stressing that placing long-term bets was harder now than at any time since the 2020 COVID-19 crisis. Markets have been on a rollercoaster ride for weeks, with world stocks rallying 20% from more than one-year lows hit after U.S. President Donald Trump's April 2 tariff bombshell, after slumping 15% in three sessions. The turbulence continued on Thursday with a sudden selloff in global government debt, the latest event to spook long-term investors out of markets that they fear have lost the anchoring force of consensus forecasts.