Why were Alfred Krupp's, John D. Rockefeller's and Andrew Carnegie's companies

considered monopolies? How did forming monopolies benefit industry leaders?

Answer: Aggressive methods of enlargement.

Explanation:

At the end of the nineteenth century, some industries created a monopoly on the market, and thus their owners gained enormous wealth. These corporations are taking advantage of the free market and all the benefits of the Industrial Revolution for the sake of enrichment. In these circumstances, many corporations do not respect business and legal codes and use the money to influence government.

On their way to power, they are "getting rid of" competitors and grabbing all market revenue. Society in America has resented this kind of capitalism. Such circumstances and public pressure led to the reckoning of governing structures with monopolistic capitalism.