I wrestled with this issue last year, when I got out of the Navy, and for me, it came down to money and job satisfaction.
My background: I have a B.S. and an M.S. in Chemical Engineering and Civil/Environmental Engineering, respectively. After serving as a submarine officer in the Navy, I had the opportunity to teach chemistry and physics at the Naval Academy Preparatory School (NAPS). I absolutely loved it.
I had no background* or experience with teaching, but found that I was very good at it. In fact, I was selected as Science Instructor of the Year twice, and Instructor of the Year once. I managed to repeatedly extend my assignment, and ultimately taught there for 7 years (5 years chemistry; 2 years physics).
As far as teaching goes, NAPS was very near an ideal environment. The students were highly motivated to succeed, and very disciplined. The instructors were available for extra instruction (EI) every afternoon for nearly two hours. There were monitored, mandatory quiet study hours in the evening. As an officer, I had nearly unlimited authority over my students, who would lose privileges for even minor infractions. Talking back to an instructor was unheard of.
In any event, all things come to an end, and the Navy was not going to keep an officer in one spot forever. As I exited the Navy, I had to decide what to do with my life.
I considered teaching public high school, but would have to jump through all of the certification hoops, and was basically looking at twice the work for half the pay. (At NAPS, I taught three sections of about 25 students each. For 4 of my 7 years, I had only one daily class prep—the other 3 years merely involved a different level, or “track.”) High school teachers generally teach 5-6 classes a day, with 2-3 daily preps. In addition, in a high school, I’d have to deal with more immature, less motivated students, not to mention their parents.
Private schools pay even less than public schools. (I knew a colleague who was offered a starting salary of $20,000 at a private school, less than 1/3 of his Navy pay.)
Teaching at the university level requires a Ph.D., which I had no interest in getting. Also, the focus at most universities is not teaching, but research.
Teaching at a junior college is usually a part-time endeavor, depending on the number of classes taught. You also generally work semester to semester, never knowing if you will be employed three months in the future.
All of this was being compared in my mind with going into engineering, which is what I ultimately chose to do.
*We did have faculty development programs in the summer, however, that dealt extensively with education theory. They were largely useless, BTW.