My mother and father both came from large families and it's interesting how they and all my cousins have turned out.
On my father's side, it's pretty apparent that none of the siblings could really stand each other, over the decades they moved all over the country, away from each other, and into wildly different walks of life. They all independently did their own thing and usually ended up in some kind leadership position (foreman, shift manager, etc.) or ended up owning small businesses (with all the risks that entails which is how we ended up homeless). They all grew up in extreme poverty in the mid-west at the end of the great depression. Of them, only my father went to college. But they all became more or less successes if you define success as "able to cover your living expenses while saving some for later". None of them became wildly rich, but all of them share the trait of stubbornness and an unbelievable work ethic.
Their kids are all generally doing fine or reasonably successful. No multi-millionaires, but all productive members of society. I'm the first person from this side to get a Masters Degree, but there are a few other college educated folks on that side. Measured by my father's side, I'm a slightly above average, but otherwise typical story.
My mother's side is a mixed bag, my grandfather was some kind of salesman and for most of my mother's generation they grew up well fed and cared for. He was a "success" by my earlier definition. But severe mental illness later in life, combined with alcoholism eventually put an end to that and my mother's teenage years was basically a collection of episodes dealing with an increasingly wildly out of control father and a deteriorating home environment. One of my uncles eventually also succumbed to the same kind of madness that took my grandfather, but the rest more or less went on to lead normal lives. But I think, looking at their lives, lots of what they chose to do was a reaction to the home environment they grew up in. One uncle ran away and joined the Army, never to return home again. Another became a minister and married into money. One took a decent blue collar job, moved away from home and worked it until retirement. Later on, they all ended up moving back into the same region in a different state (except for the military man).
The kids are mostly a disaster. Rampant alcoholism, drug-use, abusive violent ex-husbands and more. Only one went to college and she dropped out of the work force as soon as she got married right after college. Most of my cousins on my Mother's side hang out together, and all of them party together. At 30, the next oldest cousin, who grew up with a silver spoon in his mouth, has spent his career setting up chairs in hotel ballrooms making slightly better than minimum wage when he works. He went to some community college classes at some point, but eventually spent too much time drunk or drugged out to complete more than a semester. His sister, also born into money, is even worse. At almost 30, she can barely hold down a job for longer than a couple weeks. Co-dependent behavior is a way of life and they all ultimately co-support each other's bad habits. I try to avoid most of my Mother's family at all costs. I stay awake at night terrified I'm suddenly going to start getting phone calls asking for money or a place to crash "for a few days" -- because I know that will turn into a never ending drain on my family and our resources.
Measured by my mother's family I'm a wild success story - a single point of light in a dark pit of failure.
Ideally, you'd think that my mother's family, with the close family links and the availability of money through one of my uncles would have set them all up. My cousin's parents were all "success" in terms of supporting their families, but yet most of my cousins are objectively life failures.
I have people closer than my family in my life, old friends I grew up with. All of us being poor, most of them did not become successes, but it doesn't seem to me that in any case it was as a result of their parents doing more or less for them, but about their own consistently poor life choices. Ones with obvious negative outcomes, but chosen because they provided immediate positive emotional return. In other words, their decision flow chart tests if a choice feels good or not, not if it provides them with a successful outcome. Looking at my mother's family, their co-dependence and substance abuse issues, it appear they're using the same decision making process. One of my drug addled cousins suddenly deciding to stop using drugs, and move away from his group of co-dependent family and friends, and get a decent job, would be a fantastic change in behavior that I'm not aware ever happens with any frequency in reality.
It's obvious that becoming successful is complex, but I think parent's financial status is more of a correlation than a causation for future success (even though it might designate a probabilistic cap for how successful a person can become). It seems that good parenting combined with a natural desire to succeed is what happens. But when somebody doesn't have a desire to succeed, it's likely they also won't be good parents. Children pattern after their parents and also inherit the same lack of desire, from both behavior and genetic factors. Nobody has really figured out how to change that central decision point from "does it feel good" to "does it make me successful" with any sort of reliability. It seems to have to come from inside the person somewhere.