Twitter was a second tier advertising destination before there was any inkling of a Musk deal, and advertisers started leaving before the deal closed when he was trying to get out of it. The biggest advertising firms in the world are advising their clients to leave.

Why would they come back? Musk is the Donald Trump of tech - plenty of devoted fans, but not someone brands want to associate themselves with. Even if he wanted to, it doesn't seem that Musk can stop impulsively tweeting controversial things.