I agree that school performance is greatly influenced by home environment as well as other factors, but, from what we’ve seen with friends who have recent graduates, even when all of the elements are optimum, the success rate in the “real world” seems to be far less than one might expect.
More than ever before in society, kids are being told that if they do everything “by the book,” and jump through all of the hoops in school, they will be automatically be successful in life. IMO, there just seems to be a huge disconnect somewhere, based upon “real world” results.