Great list.
I had my own computer repair business ('The Computer Doctors') and had to give it up. My skin wasn't thick enough and I took everything personally. I wanted to make every customer 100% happy each and every time, and as your point #1 suggests, that is not always possible. I was eating into my profits by working longer on things and not charging more.
I found a nice full-time corporate position 7.25 hrs per day that pays well with benefits and my wife practically forced me to take it, as she saw the effect it was having on me. Even tho the monetary potential of the 'computer doctors' was unlimited, the stress and long hours were factors I had to put into the equation.
I'm happy now, only having one boss and set requirements to meet