Carnegie was a Robber Baron of the steel industry. One Reason is that he did not pay his workers enough to provide for their families. In that time period, people needed to earn about $600 a year for the average family of 6, but Carnegie only payed them about $500 a year.
Carnegie was also a Robber Baron because instead of raising his workers pay by a few cents, he decided to build large libraries and buildings where he was raised. He also donated large amounts of money to most charities and governments instead of raising pay.
Andrew Carnegie built a large country club around a lake just to show how much money he had, but in doing so, he weakened the dam that kept water from flooding into the town in the valley below. Weakening the dam allowed one thunderstorm to flood the lake and make the dam collapse.
Andrew Carnegie was a magnate of the gilded age. During the time period, he was one of the richest people alive, but under the thin cover of the rich, a whole country of low class citizens lied underneath.