In terms of quality, I mean, how many people have bad bosses who can't even manage a team of 5? In my experience, it's not always easy to find qualified people for those roles.
Now imagine some large company and I'm not that shocked that the pool of people who can effectively lead large (>10,000 employee) organizations is relatively small. It's basically a small subset of those who can lead small organizations.
And not to say unqualified people don't end up in those roles, they do. But generally I'd argue the qualifications of a CEO are likely as scarce as say the qualifications of a neurosurgeon or some other hyper-specialized technical role.
Many CEOs are, of course, very well compensated. But, whether or not you think it's extraordinarily difficult, it's certainly very demanding in terms of time and schedule.