Since businesses need to start somewhere/when and most startups fail, I think most people who even get into the role of CEO, are doing it successfully. However, this is a lot due to circumstances and many factors outside of their control. There are also many CEOs ruining their businesses with bad decisions. It is not certain, that an "AI" wouldn't do at least as good as those failing CEOs. Similarly, many developers ruin things they touch, introducing tons of complexity, dependencies and breaking user workflows or making workflows cumbersome without listening to user feedback and so on.

In short many people do a bad job and businesses are carried by others, who do a good enough job to make a net positive for the final product. Or consequences of messing up are happening slowly, like a slow user drain, or a user replacement with bad actors until good actors start to leave, or any other possibility.

About the pay argument: Well, these days you still need a good crew of developers to make the shiny AI toys do what you want them to do, so you are not replacing all of the developers, so you can't calculate like that. If we calculate some Silicon Valley CEO making 2 million and a developer making 100k-200k, then we are still at a ratio of 10x-20x. If we manage to make only one CEO obsolete or 2 out of 3 CEOs 1.5x as efficient, we have achieved a cost saving of 10-20 developers! Yay!...