American private school salaries are often lower than equivalent public school salaries, because you don't need credentials to teach at a private school, and because private schools can be an easier work environment than public schools.

I did three years in education before switching to software development. I would have done a lot more if the pay was better and the schools provided more support to the teaching staff. Sometimes I feel like I'm wasting my time working on a bunch of worthless marketing websites instead of educating people but at least I can provide for my family and live a rich and fulfilling life outside of work.

Better work environment, and private schools typically discount tuition significantly for the children of teachers. At current tuition rates, that's a massive benefit.