Why was the Great Leap Forward actually a failure and then called the Giant Step Backward?

The Great leap forward was Mao Zedong economic and social policy of modernizing china by 1988. The plan failed to take course because of poor planning, withdrawal of soviet support, natural disaster and the lack of capital. It was refereed to by factions as the giant leap backwards because of the suffering it caused especially through starvation, as it estimated that over 20 million people died.