Why wouldn't a teacher quit if they possibly could? The pay is peanuts, certainly not worth any serious immediate risk to your health.
(Also fwiw, teacher salaries in the US do vary greatly by state. You won't make off like a bandit anywhere, but it's a perfectly respectable amount in some places.)
I consider that making out like a bandit. Only 186 days of work a year, summers off, can never be fired.