Get a pay bump if you are already employed as a teacher in most public school systems.

If you are not already employed as a teacher in the public school systems, it makes it harder for you to find a job as such (at least during a budget crunch) since you come with a higher price tag.

I had a teacher in high school who had her Ph. D in education. She was an immigrant from Greece, and did her Ph. D on ways education could help immigrants make the leap from immigrant to citizen based on her experiences (I don't recall the specifics - high school was a long time ago). For what it's worth, she was the government teacher.

I also have a friend who's getting his Ph. D in early childhood education largely because, after something like five years as a kindergarten teacher, he was astounded at how dumb the other teachers were (he tells stories of co-workers not being able to do basic arithmetic) and how much they depended on materials to actually do their instruction. He views the Ph. D largely as a way to get his foot in the door at someplace where he can design and produce early childhood curricula and help save kids from teachers who have no business in the classroom.

Then again, he also spoke frequently about how much he hated the professors when he was in college because many of them had literally never taught children. They got to college because they had good grades, went to grad school because they had good grades and got professorships because they did good research, but never had to apply what they were studying.

Honestly, it sounds a tremendous amount like computer science.

Become an academic in that field - that is pretty much what a PhD is - credentialing for academic research.