He could also take higher risks, since he knew that there was a security net to catch him. Much easier to make high risk/reward decisions, if the risk (e.g. going broke) isn't actually real. He presumably also had an above average education and many other benefits. This is also why many rich people might end up building successful businesses. The average person might get one shot and either makes it or goes broke. The rich person can roll the dice multiple times (and might have learned something from the last try).

Also disregarding everything even, if he had succeded: That would still only have been a sample size of one. I doubt anyone is saying that you can't under any circumstances pull yourself out of poverty, but on average the cards are just stacked against you in many ways.

Also i doubt that reselling second hand stuff is a viable business model for a larger group. Like sure in a large city a few people might be able to carve out a niche for themself, but the more people do it or the smaller the market, the less it works.