Ask most homeschooling American parents (which is becoming a big thing now) and they will not answer that. Many are since the school system is lacking (and fighting it takes as long as the child's education if not longer). Others are due to the child needing specialized care that the system does not/cannot provide, examples being that the student had ADD/ADHD, on the autism spectrum, is gifted and bored but the school has no advanced options. There are many online/mail schooling options that help parents with topics, but also open the parent to create their own lessons (going to museums, go to a hacker/maker group, travel etc) that might be more hands on. There are also many homeschool groups where parents rotate teaching and opens up for 'socialization' (for those that worry about that issue). I'm not disagreeing that there are groups that are extreme, there will always be, but assuming that the majority are extreme and want to 'indoctrinate' with 'weird' beliefs is rather uninformed.