Students get to learn so many things in school which they can never learn at home. They learn to communicate with other student and schools helps student to build confidence as well. If students does not attend school then it will be very hard for parents to handle them with studies and every thing.
Children need to learn the basics of life. Maths and English. Those are things you learn at school. If you don't learn English and you are writing an significant email to the prime minister, How would the react? If a person doesn't learn Maths, How would they pay their bills, If they didn't know how to count money. Finally, A person would need to know how to count money to do their everyday shopping.
There is a point in time when school truly becomes irrelevant for students. I'm in year 12 and I know for a fact that during these few periods of time school become more of a nuisance than a support. Studying alone or with a few friends was much more convenient than attending schools. There was no additional pressure from "homework" and concentration on studies was much simpler. School is definitely useful to learn the basics when studying for exams or special tests school becomes annoying