Bandits happen when a creature's way of life is so thoroughly and quickly shattered that they can't even begin to adapt. It happens with both animals and humans, the difference is only looking at it as an ecosystem or an economy.
Too many bandits will obviously cause the system to collapse, but a strong system is one that can handle a few bandits and still function normally. It's not particularly more or less human to devolve into banditry, it's just that a system that collectively has a lot of those edgelords will die, and only the people who managed to get civilization up and running will survive.