The author uses many details to point out General Zaroff's wealth and that he is well educated. In the following paragraphs I will point these out.
General Zaroff was very wealthy. For one thing, he purchased the island and had a mansion built there. There were, however, more subtle details such as the silk PJ's he let Rainsford wear to bed. There was the suit Rainsford was given to wear, the foods they ate, and the champaigne.
Details were also given that indicated that he was well educated, such as Zaroff asking Rainsford how he could hold such ideas about the value of life. He was a good observer, and knew what to make of the observations. He also had the ingenious idea of putting up lights to indicate a harbor where one didn't exist.
As you can see, Zaroff was wealthy and well educated, but he didn't use them for the right purposes.