So an acquaintance decided on a career change? Your point is?You seem to think your personal situation applies universally to all mathematicians. It doesn't.
An acquaintance abroad quit a good job as an electrician in his 30s to do a BA and after the BA took a teacher training degree to become a secondary teacher, five years of study. A mathematician could do a one year teacher training course some years ago. Today,thanks to pressure to create barriers to entry to teaching, a two year course is required despite lack of empirical evidence that teacher training is effective.
Must I repeat that high qualifications in a subject do not make one qualified to teach young people.?
Your OP suggested bringing in contractors, of which I am one. There is no way that I will take two years not only unpaid and with no access to benefits as well as paying for further education in order to subsequently take a pay hit. Nor do I know anyone in my position who would be remotely interested in such a prospect.