I'll use the relatively non-controversial example of the Chinese. In Malaysia, they're a small minority of the population yet totally dominate business.
Why? Because they are extremely entrepreneurial, work crazy hours, and do this consistently up and down, from the tiny boutique in the streets to the multinational.
Why? I have no idea. But somehow its ingrained in their culture. I don't believe they have a special gene that uniquely benefits them. They're simply culturally centered around business and productivity.
On the opposite end there's the culture of apathy. To live by the day, accept one's state even if bad, and to make zero effort to improve it, even if opportunities present themselves.
These cultural differences very much exist and are plain to see and replicable, and lead to drastically different outcomes. But I guess simple truths are too controversial now, so let's go with the "systemic" nonsense.