I don't think he's saying that being a CEO is harder than being a parent or teacher. His main point is that CEO's often underestimate the mental/emotional strain that comes with their role. It's true that people who are fired have to live with the consequences - but they usually have friends and family to empathize and support them. Nobody is going to listen to a CEO's sob story about how hard it was to lay off someone - but the fact is it's quite painful.

When I was running the Stanford Daily, we were bleeding cash and I had to lay off a 65 year old lady who had been working at the company for 10 years. She was reliable but did poor work and was costing the company tens of thousands of dollars annually. That conversation was not fun and the entire process was stressful. I can't imagine having to lay off an entire division, especially of people that I hired.