From what I've seen, being a CEO, CTO, etc is almost inherently a glass cliff. You either keep things running smoothly or you will get let go. Besides, Ellen wasn't even fired. She resigned no?
"Resigned" is how executives get fired.
A little background: at this company, "engineering" included not just development and QA, but also customer support, IT, and shipping & receiving (but not documentation or product management, both of which were under marketing). Also, for some reason, the operations people of our offshore office also reported to the VP of Engineering instead of our corporate management. He had a lot of power just based on of how much of the company reported to him.
The VP basically turned the technical side of the company into his own personal fiefdom. He took the idea of acting as a filter (which is a good thing) and took that to such an extreme that he was acting as a brick wall (which is a bad thing). It was almost impossible for product management or sales to find out what we were doing, and we were mostly kept in the dark and drip-fed small details about the business side of things. Worse, he would start projects without the rest of the company's knowledge and tell us the order to create them came directly from the board (in reality, he was trying to impress the board). At one point, he conceived a project, sold it to a customer, and then started development all without sales, marketing (including product management), or the CEO knowing about it.
Eventually, the CEO had enough and asked him to resign. He gave the VP a month to announce his resignation and leave. Guess what? The VP just sat on it and acted like it was business as normal. A month later, the CEO had him walked out first thing in the morning and had one of his most loyal executives distribute the new org chart containing a massive amount of changes to prevent so much of the company from being centralized under a single VP ever again.
(In case you're wondering, the company has since had a successful exit, by the way.)