The wealth gap comes down to monopoly velocity: Rockefeller's Standard Oil controlled 90% of U.S. oil refining at peak, giving him pricing power that generated $90 million annually—essentially a tax on every industrial operation in America. Carnegie's 30% steel dominance, while impressive, faced fragmented competition that capped his margins. Oil flows through every machine; steel builds them once. Rockefeller's recurring revenue model crushed Carnegie's capital-intensive, one-time-sale business model.

Rockefeller also played the consolidation game more ruthlessly. He didn't just dominate his industry—he systematized it through aggressive acquisition, rebates, and market manipulation that created structural moats competitors couldn't breach. Carnegie, for all his genius, was competing against other steel magnates with similar cost structures. Rockefeller essentially eliminated the concept of competition in oil by making refineries economically pointless to operate outside Standard Oil. One guy built better steel; the other guy built a tollbooth on energy itself.

Here's the kicker: the inflation math actually favors Rockefeller even more than the nominal numbers suggest. His $340M controlled a larger economic share of GDP and generated more annual free cash flow than Carnegie's $372M. Rockefeller's wealth was *compounding faster* because his monopoly rents kept rising. Carnegie's steel profits were getting pressured by new competitors and technology shifts. By 1920, adjusted for actual economic power, Rockefeller had lapped him—making him arguably history's wealthiest person in terms of real economic dominance.