I would say it is a bit of both.
I’m with you, it is not black and white, either or. I would say the average direction of your financial state is a function of work ethic. A person born to poverty and a poor work ethic will stay poor while a person born poor but with a good work ethic will move upward at a rate commiserate with their talents. On the other side someone born wealthy but with a poor work ethic will have their wealth decline with a rate determined by their vices while someone born wealthy with a good work ethic will maintain or improve on their wealth depending on their own talents.
Random factors like accidental setbacks and opportunities available also play a role, but mostly are perturbations on the larger trajectory. Wealth also grows somewhat exponentially since as you gain more wealth a larger and larger portion tends to be invested in sources of wealth and not into consumption.
At a societal level though, we cannot excuse and encourage sloth by blaming someone’s conditions. We must encourage hard work and remind everyone they can move forward based on what they do with what they have. The Democrat way fails on both counts.