In The Men Who Built America episode 3 when Carnegie built his steel mill what was wrong with his timing

In this episode, there is more actually "right" with Carnegie's timing than "wrong."  America's railroad industry is growing exponentially and the nation needs steel for high-rises.  Thanks to Bessemerization, steel can now be produced much more cheaply than ever before.  Carnegie is able to control the raw materials by buying iron mines and stores of coke, which is the coal used for its ability to generate the hot temperatures needed to burn off impurities in iron.  Carnegie is also able to take advantage of a large pool of cheap labor, as immigrants from Europe and displaced Southerners (both white and black) come North for a better life.  The only blemish against Carnegie in Episode Three is a flashback to Episode Two when Henry Clay Frick does not handle the strike at the Homestead plant properly and it leads to bloodshed and a blemish on Carnegie's record.  This leads to a permanent rift between the two men, but Carnegie's personal fortune and philanthropic interests are not harmed by the Homestead incident.