In 2021, Lisa Chen, a software engineer, started a new weight-loss medication. Then, something interesting happened at her local coffee shop, her employer's healthcare costs, and the global economy.In six months, Lisa stopped buying her daily morning muffin, causing the coffee shop to lose $600 in annual revenue from one customer. Within a year, she canceled her beer-of-the-month subscription and stopped ordering late-night DoorDash. By 2023, her grocery bill dropped 40%, alcohol spending fell 8...