Final answer:
The owners of the key gate became rich men because they had the right combination of skill, ambition, and luck during a period of tremendous financial rewards in the late 19th century.
Step-by-step explanation:
The owners of the key gate became rich men because they had the right combination of skill, ambition, and luck during a period of tremendous financial rewards in the late 19th century. They were able to turn inventors' ideas into industrial growth by investing in industries like steel production and oil refining.