I was "unschooled" for some years. I was near the top of my class at school (not because I was smart, just because I paid attention and worked hard), and hence my teachers gave up on me. Expending time on a kid who is likely to get A's without intervention does nothing to improve the school's metrics/ranking.

I would have been fine in a good private school but my parents weren't rich and couldn't afford the fees. Somehow I convinced my parents to let me educate myself, and at least for me it was successful. I finally had time to teach myself programming, which at the time was not taught in school.

Would I recommend it to others? Kids should try school first and see if they benefit from it. Some kids love school and do very well out of the system. However, if school is failing your kid, they might be better off without it.