Aside from the socioeconomic circumstances of one's birth, luck favors the prepared. I also come from a poor background and got "lucky" a few times in my life (in particular the sequence of events leading to me joining a US tech company while making web apps in Russia was rather tenuous), but the cause for the luck each time was prep.
E.g. I aced an interview question on GC design because, after doing some GC tuning for a web app at work I read GC docs and then a couple research papers at home to understand it better. After the (group) interview loop, someone told me they were asked a hypothetical SQL backend design question they had trouble with, and I realized I knew then how SQL Server solved that, for similar reasons, so I could have aced that question too.
Sure, I could have gotten yet another design question that I knew nothing about ("unlucky"), but to even have a chance to get "lucky" you need to prepare... to win the lottery you at a minimum need to buy a ticket ;)
As for the luck of the birth, almost by definition, when you are poor you grow up surrounded by people in similar circumstances; if you "make it", it is very easy to judge those who didn't, because well, they were in similar circumstances to you and you saw what they did differently, often in detail.
E.g. I aced an interview question on GC design because, after doing some GC tuning for a web app at work I read GC docs and then a couple research papers at home to understand it better. After the (group) interview loop, someone told me they were asked a hypothetical SQL backend design question they had trouble with, and I realized I knew then how SQL Server solved that, for similar reasons, so I could have aced that question too. Sure, I could have gotten yet another design question that I knew nothing about ("unlucky"), but to even have a chance to get "lucky" you need to prepare... to win the lottery you at a minimum need to buy a ticket ;)
As for the luck of the birth, almost by definition, when you are poor you grow up surrounded by people in similar circumstances; if you "make it", it is very easy to judge those who didn't, because well, they were in similar circumstances to you and you saw what they did differently, often in detail.