No, you are right you can do everything right and still end up unlucky. That's the hard (awful?) part of life.
But that's an individual path. In aggregate there are statistics that can help us choose and recommend which path to follow. And the statistics show that people with an education are dramatically and earn way more successful than people without.
Are the smartest, the most hard working children the most successful in adult life? In average yes.
and you can add: are any dumb and lazy children successful in life? only if they have rich parents. so while working hard doesn't guarantee success. not working at all pretty much guarantees failure.
Child can work hard, get education, get degree and end as broke person with low paying job. Like being a teacher at school.
Are the smartest, the most hard working children the most successful in adult life? Not really