A social media spat between Elon Musk and Jeff Bezos this week underscored a sharpening rivalry between two of the world’s richest men at a time when both are trying to grow their sprawling businesses empires in President-elect Trump’s second term.

The world’s two richest men are longtime business rivals, but now one of them has the ear of the next president of the United States.

Musk’s assertion goes against the actions of the publicly apolitical Bezos this election cycle, as the Amazon chairman reportedly killed his Washington Post newspaper’s endorsement of Kamala Harris.