None of us here really do, but im willing to think that whatever it is they do do, doesnt deserve anywhere near the amount of money they take home.
I know exactly what they do, as I've reported directly to CEO's during a lot of my career and been close with several CEO's including my cousin, Charles Maddy, who is CEO of a sizeable regional bank. My wife is also in upper management, and has been good friends with many CEOs and will probably be a CEO herself before her career ends. But as to what they do, the job is entirely about meetings, planning, delegation and communication. Also, the golf thing is just a stereotype. I think I probably played more golf than any of the CEOs I've known.
What you really need to understand about CEO's and how much stress they are under is that every single thing that happens with that company is their responsibility even if it isn't. For instance, if a customer slips and falls on an icy sidewalk, or if a mistake is made on a product, or if a customer service rep is rude--anything--it all is the CEO's responsibility because the board of directors and shareholders will rake him over the coals about it. This causes extreme stress. Imagine you suddenly find out that a few guys in one department have been harassing the women there. That's your fault, too. In fact, you almost may as well have done it yourself.
Now, does that extreme stress mean that they deserve their crazy salaries and bonuses? No, probably not, but it's just unfair to say that they don't work hard, etc.