Billionaire business mogul Mark Cuban was with “Extra’s” Renee Bargh on the set of his hit ABC show “Shark Tank,” where he is never afraid to share his honest opinions when contestants pitch their ideas to him.

When Renee asked Cuban about his former friend, Republican presidential candidate Donald Trump, he held nothing back. He said, “You know what? It’s rare that you see someone get stupider before your eyes, but he’s really working at it…You have to give him credit. It’s a difficult thing to do, but he’s accomplished it.”