we moved from london to the home counties because we thought the DC would have a better quality of life and smaller, more human schooling. Ex and his sibling had gone to private school, I had gone to state grammar. Pre-DC I had been a teacher in state schools in London.
In the 18 months before my eldest was due to start at the local high school it went through 6 heads. One removed, one had a breakdown, two were just temp anyway .... the kids were being let down. Due to catchment policy this was our only state option (unless we suddenly converted to catholicism and sent them via a 40 min train journey to a catholic high school in a neighbouring town). So we went private, despite my Ex saying he would never put his DC into private school (He hated it). I pushed for it because I know what a good school looks and feels like and I know what a failing school is. We could only do it with support from Grand Parents.
I think the private school was brilliant for one of my DC, fine for another and maybe not so good for the third whose friends were mainly in the state school and he missed them.
We make the best choices we can for our children in the situation we find ourselves in. Anyone who doesn't is not a good parent, surely? If private looks to be the best choice, for whatever reason, then that's the choice you make if you can afford it. It might be the wrong choice, you just have to go on what you know at the time.