Family backgrounds plays a part, but, not entirely.
I have friends who parents are rich, from school to NS. I can say, most of them are wasting theirs parents money and time. Buying and changing sports car, tuning, modifying. Fooling around with girls and clubbing. Studies wise, keep changing course and switching school, if not, fail and keep retaking the papers.
And I also have friends with complicated backgrounds, abusive fathers, gambler and so on. What are they now? Just started work and their salary range is 3k plus per month. Different people see success differently, to me, 3k might seems little, but in my eyes. They already succeeded in life.
Those rich kids with sports car and slutty looking gf fail IMO.