For reference, Rockefeller was worth $1.4 billion in 1937 dollars on his death. That is the equivalent of $31.36 billion today. The richest person, Elon Musk, is currently worth $400 billion, or nearly 13 Rockefellers.

Nothing humanity has ever seen really compares, unless you're looking at literal kings literally enslaving and literally extracting all value from an entire population, and even then the scale will be far lower given population growth. We are in the oligarch golden age, and if we're lucky and we don't stay here, people will look back at this moment, and not the robber baron era, as the historical comparator for grotesque wealth accumulation.