Teaching, as some people said, is a noble profession whereas the teachers have the main job to educate students to become better persons, even to be better than the teachers themselves.
Teachers have lots of things to do and probably it is one of the most stressful jobs in the world. Don’t you think so? Teachers have the burden to educate, facilitate, develop, grow, … (you can add the terms) children/students to be the best they can become. They have the responsibility (or so to speak, the pressure) to, in a way, create the future of the world within certain boundaries and system established. They are paid to do so. If students fail, mostly people will criticize schools and teachers. If the quality of the graduates is not up to a certain standard, guess who will be blamed and criticized?