Were the industrialists of the late 1800s captains of industry or robber barons?
The best answer to this question is “yes.” The industrialists were both “robber barons” and captains of industry.
The industrialists of the late 1800s can be seen as robber barons. They used whatever tactics they could think of to drive their competitors out of business. They relentlessly pursued as much market share and as much profit as they could get. That is how Rockefeller’s Standard Oil came to control over 90% of the market for refining petroleum in the US. They also were willing to take harsh actions to keep their workers in line. Carnegie’s actions in the Homestead Strike and the actions of the Pullman Company in that strike are examples of this fact.
But the industrialists were also captains of industry. The competition they engaged in drove down prices for consumers. They created economies of scale that were beneficial to the country as a whole, allowing things like the building of the transcontinental railroad. Furthermore, they were major givers of philanthropy. Carnegie built thousands of public libraries. Rockefeller created a charitable foundation and also created a university (the University of Chicago). These were not men who were hoarding their money.
So, these industrialists should be seen as both captains of industry and robber barons.