Social media users around the world took out their popcorn, flocked to their devices and chimed in as the feud between the president and the billionaire played out.

An intense public feud erupted on Thursday between President Donald Trump and his one-time ally, billionaire Elon Musk, with an argument about Trump’s massive tax and domestic policy bill raging across social media and in the Oval Office.

What began as Elon Musk's embrace of right-wing populism has become a defining — and potentially harmful — chapter in his business career.