A lot less than most people seem to think. By far the best predictor of someone's wealth is their parents' wealth. By very far. The vast majority of wealth is generational.

But even if you believe in upward mobility, the point is that needs to happen first before you possibly have time, energy, and money to devote to your passions. It's not backward; if you'd argue "no, succeeding in your passions is what enables upward mobility", then you (A) are thinking of a very small subset of highly marketable passions, and (B) have identified the catch-22 that makes upward mobility so uncommon.