What should a city do when the people that pay taxes and keep the machine chugging along decide to leave because the city is becoming an unbearable mess? It's

What should a city do when the people that pay taxes and keep the machine chugging along decide to leave because the city is becoming an unbearable mess? It's an honest question. Social programs cost money, and the money comes from taxes. I am generally in favor of drugs being legalized and drug addiction being treated as a healthcare policy concern instead of a criminal concern. But the experiment seems to fail more often than not.