Because the pay sucks ?
That's why I didn't teach. Went all the way to my senior year, got high praise from others for my classroom management skills and perception, my "student-teacher" instructors thought I was a natural.
Then I realized I would need a second job just to eat in most parts of the country.
Sorry, couldn't do it. My day started at 7:30 a.m. and usually didn't end till 8:00 p.m., after grading 150 papers, writing tests, lesson plans, etc.
Did I love it? Heck, yes, I loved it. Would I have burned out after a few years. Probably.
Did I make more money moving into another field. Goodness, yes, gobs of it.