Going to school is not all about learning subjects, you also build character out of your kids. There they learn failure and how to cope with it. Thats one thing you cant teach at home no matter how good the tutor are.
The most talented of their abilities without communicating with other people, if they do not want or are not interested in learning, if there is no certainty of a direct connection between study and life success, and also the ability to beat in society.