For example, just after Ulysses S. Grant was inaugurated as President, financiers Fisk and Gould engineered a gold squeeze that brought the US financial system into crisis and threatened the entire US economy. Today they would be prosecuted as market manipulators. The Grant administration was also marred by the Credit Mobilier scandal in which members of Congress were given bribes and interests in the railroads that they subsidized through land grants.
Rockafeller became immensely wealthy by consolidating ownership and gaining control of the US oil industry. He ruined competitors by sending thugs to blow up their wells, pipelines, and refineries, while railroads were induced to bar or overcharge competitors who relied on the rails.
Edison was clever and hard-working as an inventor, but he was greedy and dishonest as a businessman. He frequently cheated employees, business partners, and customers and abused the patent process to suppress rival inventions. Tesla began as an employee, was cheated by Edison, and then left to pursue his own inventions.
As academic economists point out, free markets depend on the rule of law, with contracts and regulations reliably enforced, and competition and innovation fostered and protected. Yet in the Robber Baron era, bribery and conflicts of interest were routine and normal, with police, prosecutors, judges, and legislators threatened and bribed to accommodate crooked business methods.
The public knew this and wanted it to change. That became one of the driving forces of the original Progressive movement. For many Americans, the attraction of socialism was not redistribution but as a critique and weapon against the corruption of the Robber Baron era. Pretending that there were no Robber Barons contradicts the facts of history and loses much of the argument by default.
Folsom is right. The “robber baron” myth is an attack on free markets.
https://mises.org/library/truth-about-robber-barons