Tom poorly managed this economic situation. When we paid for the buffet beforehand, it became a sunk cost. A sunk cost is a cost that has already been paid and cannot be recovered.
He used this sunk cost to influence his future actions, which was a mistake. Once the money is spent, it's gone from his possession. He instead should've just enjoyed his stay at the buffet (with his best friend).
Tom's buffet money can now not be used for any future opportunity costs because it has already been spent. An opportunity cost is the highest-valued alternative given up in order to engage in an activity.
Who knows? This money could've been spent to further his dream of becoming an entrepreneur, an operator of a business. He adores making soaps for his loved ones and friends but would love to sell them.
Too bad he isn't a monopoly though. Monopolies are formed when a firm has complete control of a key resource, network externalities, natural monopoly, and government restrictions on entry.
But what do I know? I'm only a microeconomics analyst.