They got wealthy by making smart decisions like these. They’re not trying to avoid paying a fair price, they’re trying to make sure they don’t get gouged when the buyers realize how deep their pockets are. I would challenge you to consider whether your statement was made with reason, or with a learned hate for those wealthier than you.
I don’t understand… Was he morally obligated to disclose the fact that he wants to build a large underground structure for some reason? Does that change the fact that they have land they want to sell, and he wants to purchase it?