You win some, you lose some. When Elon took over Twitter, he made a number of drastic changes. Some of them were successful, while others were less so. Anyway, his plans are for the long term and therefore I don't think that he will be much worried about the temporary setbacks. The core point here is that Twitter retains a monopoly in its respective domain. There are simply no competitors for Twitter in the micro-blogging platform. And if the situation remains unchanged, the advertisers will return to Twitter sooner or later.