Success (well, the generally accepted version of it in our society) is a mixture of things.
Your starting conditions
Your temperament
What happens along the way
How you deal with it (which is influenced a lot by 1 and 2.)
It's undeniable that your start in life is a huge factor. I'm from a poor and not terribly functional background. I've done ok because:
I was lucky enough to be born well above average intelligence
My temperament is of the stubborn but flexible type
Nothing too dreadful has happened to me
I'm well aware that if I'd had a more stable upbringing and better educational opportunities I'd have done better. I did go to uni (multiple times) but it was a financial and social struggle. I saw there that those who expected to go saw it very differently than I did
I'm also aware that my upbringing could have been much worse. I could have had a truly terrible time of it, or I could have been born a girl in a grim bit of tribal Pakistan. What would my chances have been then? Or I could have developed a life changing illness. Or become disabled.
Success is a mix of factors. It's rarely all luck unless you're of the dim but billionaire Ilk. It's rarely all circumstance, although there are people who have pulled themselves up from some dire situations. For most of us it's a mix, although that mix varies with where we started.
What can we DO about it is the question.
We can ensure that families that need it have early, quality intervention. Closure of sure start centres is insanity. We can ensure that all children have equality of opportunity in education. It's obscene that abpoor child is expected to put up with what might be a sink school and low expectations while a rich child's parents would have the resources to educate privately. ALL schools should be of high quality with free school meals, and wraparound care and high expectations for children.
Reducing child poverty would help
Moving us from a low wage low skill economy to a more skilled higher wage economy would help.
More help for drug and alcohol problems
Better housing
Better schools
Less inequality.