Former President Donald Trump criticized billionaire Mark Cuban in a recent Truth Social post, labeling him a loser and claiming he refused to take Cuban's phone calls while in office. This feud escalated after Cuban mocked Trump’s tariff proposals during a Wisconsin rally for Vice President Kamala Harris. Once allies, the two billionaires have shifted dramatically since 2015, with Cuban now actively supporting Harris. Trump has aligned with Elon Musk, deepening the rivalry between these influential figures.