I worked for a startup for several years, as the fifth hired software developer and got to see our CEO fired within the first eighteen months. They were not the founder, but they had hired the VP of Sales and the entire sales team who were also all let go on the same day. Luckily the core product wasn't impacted and our primary clients probably didn't care.

The company hired two more CEOs over the next three years, each of which lasted less than six months. I'm not convinced that the new CEOs ever actually did anything, although that is possibly due to the board running interference.

My two takeaways from this experience are that if you are a founder you don't want to be CEO, and CEOs are basically useless.