Lucius Malfoy disguised himself as a businessman from Britain and chatted with the people in the garden. When he found someone who might know more, he used spells and Veritaserum so he could "pry" information out of them.
Severus had no interest in his "game" and smoked by himself off to one side.
According to the ideas of Adam Smith and others, pursuing personal gain would ultimately advance society's interests. We could drink milk and eat pork not because dairy farmers and butchers bestowed them upon us, but because they, too, were pursuing profit.
Yet when everyone blindly pursued the maximization of personal interests, it did not always maximize society's overall interests. Quesnay's economics had been intended to give farmers a good life, but it drove grain prices away from reality. City residents simply could not afford them. Nor did grain prices fall according to market forces when supply exceeded demand. Even when vast amounts of grain arrived, some people hoarded it, creating a false impression of scarcity. The highest bidder got it.
Below were citizens so hungry their eyes gleamed; above were rich men feasting on delicacies every day. When people lost their reason, they could do anything, including robbing grain carts. Hunger, agitation, excitement, and nervousness robbed an irritable crowd of its ability to think. What they did ran completely contrary to their goals. In towns where goods could not arrive without military escorts, merchant caravans simply stopped coming. Those who gathered to make trouble received even less bread than before, so they left the cities and became refugees, searching rural households for grain. In their eyes, those people were in league with the hoarders. Farmers did sell grain from their homes or inns, but the army also requisitioned and demanded grain. This vicious cycle plunged the people