those who can't do, teach

Proverb

 * 1)  It is easier to get a job teaching how to do something than to get a job actually doing that thing.

Usage notes

 * This is often used to attack the competence of teachers in technical fields where teachers make less money than workers in those fields, the presumption being that no one would take a lower-paying job if they had the skills and training for the higher-paying job. Whether this is true is disputed. Aristole's original observation was "those that can, do; those that understand, teach."