All three of my kids (now adults) got schooled at home, then went on to college. More unschooling than homeschooling -- we didn't follow a formal curriculum. Of the group of homeschooling families we socialized with in Portland most of the kids went on to college. Back then we would get college recruiters, including from Ivy League schools, showing up at homeschooling events. I suspect that has a lot to do with the relatively affluent middle class who can afford to homeschool, but it helps that homeschooled kids actually perform well at college.
You can find some videos and accounts of unschoolers with feral kids who can't read. That happens too but not the norm in my experience.
If you haven't already found them, get John Holt's books, especially How Children Learn and How Children Fail. Also Grace Llewellyn and John Taylor Gatto. I liked the book Deschooling Society by Ivan Illich.
Ask any public school teacher and they will tell you that the number one determinant of success for a student comes down to parental involvement. They might also tell you that school administrations ignore and sometimes actively fight against parents getting involved. Homeschooling just takes parental involvement to the extreme. Public school has a lot more to do with keeping kids off the street and giving parents the hours to work -- day care -- than with education. Some kids get lucky and get a lot out of school, but a lot more don't.
