Selznick built his fortune on production—he was the ultimate auteur-mogul who squeezed every ounce of creative control and prestige out of individual films like Gone with the Wind, but that model is inherently feast-or-famine. He'd sink $4-5M into a single picture (astronomical for the 1940s), meaning his wealth was concentrated in hit-dependent blockbusters rather than a consistent revenue stream. His obsessive perfectionism, while creatively brilliant, meant he couldn't scale efficiently—he couldn't produce five films simultaneously like a true studio mogul. By the 1950s, as his independent production company struggled, his net worth actually declined relative to peers.

Mayer, conversely, owned MGM outright and controlled the entire factory. He didn't bet on individual films; he owned the actors under long-term contracts at pennies on the dollar, owned the directors, owned the distribution network, and owned the recurring revenue. MGM was churning out 40-50 films annually, which meant Mayer's 1950 peak of $60M wasn't from one Gone with the Wind—it was from systematic exploitation of a vertically integrated studio system. He took a percentage of everything, and "everything" was massive and predictable.

The $130M gap ultimately reflects the difference between being a brilliant producer versus being a ruthless monopolist. Selznick was richer per film, but Mayer was richer per year, and compound that over decades of studio ownership and you get a 52% wealth advantage. Mayer's brutality—the iron-fisted contracts, the blacklisting, the actor control—was ugly, but it was efficient. Selznick's perfectionism was art; Mayer's monopoly was business.