The five year teacher attrition rate is under 20% based on this study: (https://edsource.org/2015/half-of-new-teachers-quit-professi...) That's rather low and includes many who don't like teaching even if they have the skills. Which suggests most people really can do it.

Granted, that's not the first time these people have been in a classroom, but collage Education degrees don't see high attrition either. Also, "97 percent of teachers who earned more than $40,000 their first year returned the next year, compared with 87 percent who earned less than $40,000."