You did not mention good looks. We have a question: Is education associated with improved life outcomes? Somebody gathers data and finds that people with more education tend to have better outcomes than people with less education. That is evidence that helps us answer the question. It does not tell the whole story. Perhaps being tall helps too. (Seriously.) We assume that there are both tall and short people in both the dropout and graduate groups, so any height effect will cancel out. This might be a bad assumption, and we would have to ask another question and gather more evidence to find out. We will never determine all the ingredients that contribute to each success; that would require a biography of every individual. But that doesn't mean we can't make justified generalizable conclusions with some level of confidence.I think my current circumstance is a combination of hard work, good choices, and luck.