I don't believe that. The average CEO is going to have perhaps ten direct reports. I'm willing to bet nearly every one of those is capable and up for the job.
In my past I got high enough to barely touch the ceiling of a multi-billion dollar public company. I routinely had 1:1s with directs to the CEO. Not one of them would be willing or able to take that CEO job.
Just the amount of public facing interviews on CNBC would disqualify half and the other half wouldn't want to do it. They were already being paid very well.
CFO or CTO or CISO gets compensated, and they have significant challenges and stress.