I would say about 50% of the head coaches at our high school are teachers, which is awesome to have a connection to the school, someone who also interacts with the kids at the school. The rest are people from the community, and there is lots of turnover. The sports that my kids have played fight every year to staff teams at various levels, and it's a nightmare as you wonder if a team will have enough coaches. The pay just isn't there, and the commitment (generally right after school) is tough for almost anyone that isn't retired or a teacher.