Or to take blame for past company performance, or for political reasons, or whatever. All of that might fall under "someone else can do better." Sometimes execs are fired for making bad decisions, whether fairly or unfairly.

If the police want to pull you over, they can always find a reason. Same with a board firing an exec. Whether the nominal reason is the same as the actual reason is pretty hard to tell from the outside.

Again, that's the gig, and if someone doesn't want the uncertainty or the downside risk, they can hand the compensation back and do something where performance is more measurable and treatment is more equitable. By the same token, my view of a "successful exec" depends on repeated success over time, not just a hot IPO or a good quarter.