It's a likely theory. But economics teaches us when a player overcharges, others will step in to undercut and take all the market share. So, we're at a point where we need to admit that mantra isn't true in the modern age, or admit that we've done a terrible job at preventing effective monopolies/duopolies from forming.
Why not both? The modern dismantling of antitrust regulation and enforcement is a significant driver of both. It's gotten way worse now than ever, to the point where private equity firms like Vanguard and Blackrock can be the biggest shareholders in direct duopoly competitors (KO and PEP are an example), or where investors and producers are permitted to fully horizontally and vertically integrate (AMZN is an example)…
US real gdp is 10x what is was in 1947 [0] (FRED only goes back to 1947). Add in the extra 18 years and the fact a bunch of companies are now global thus expanding their markets and those revenue numbers don't look so surprising.
Also, why'd you pick the start of the great depression as your start date?