Former President Donald Trump launched a scathing attack on fellow billionaire Mark Cuban on Saturday, accusing him of being a “loser” and a “weak and pathetic bully.” What Happened: Trump escalated his public feud with Cuban after the latter’s criticism of the ex-president’s tariff proposals during a Kamala Harris campaign rally in Wisconsin the previous Thursday. Trump used his Truth Social platform on Saturday to lash out at Cuban. “Mark Cuban is a Loser,” Trump wrote. “Wouldn’t take his phone calls anymore while at the White House, and he went rogue. A weak and pathetic ‘bully,’ he’s got n…