New York City Mayor Zohran Mamdani's central promise has been to bring down his city's cost of living . But New York's affordability problems are a result of its own success: Despite slowing population growth , the city's housing stock and services are still in high demand, pushing prices up. Cities typically get cheaper when people don't want to live in them anymore — think of Detroit, after its downfall — and not when they're in high demand and growing. So the question becomes not whether