Final answer:
John D. Rockefeller and Andrew Carnegie were called Robber Barons because they used ruthless business tactics to enrich themselves.
Step-by-step explanation:
Robber Barons: The Explanation
John D. Rockefeller and Andrew Carnegie were sometimes known as Robber Barons because they used ruthless business tactics to enrich their business holdings.
They would employ tactics such as monopolistic practices, undercutting competitors, and exploiting workers to gain control and increase their wealth.
While some argue that they were innovative and highly successful businessmen, their aggressive strategies often came at the expense of others and led to a concentration of wealth in their hands, which contributed to social and economic inequality.
Learn more about Robber Barons