Here are a few examples from people I know:
- English teacher turned paralegal in large firm, now runs the firm's staff side.
- Geography teacher who knew GIS started out working for a business site planning firm, then spun off his own shop.
- Started nonprofits in their area of interest, x2 or 3.
- Went to law school, x3 or 4.
- Language arts teacher turned contract writer for websites.
- Math teacher turned money manager for government, x2.
- Industrial arts teacher turned contract groundskeeper for cemeteries, which he's grown into a business with a couple employees.
- Spanish teacher who presented herself as an online marketing consultant with zero formal training, and now has way more work than she can do.
- Social studies teacher taught himself SEO work, got a job with a small shop, and spun out on his own after a few years.
- Industrial arts teacher took over the family farm.
Those are the people I can think of off the top of my head.
And for context, I'm 40. Of the many people I know who started in public school teaching after college, I can only think of one who is still in the classroom, and she's actively looking for a way out. The rest have all either gone to admin, gone to very nice private schools, or left education.