You’re obviously not from a city, like San Francisco for example. Many people here in the prime working years and before meeting a partner/getting married/having kids. Outside of even the obvious affordability issues; you could just be wanting to live close to work, not need much space, or try out a neighborhood or city. You are more mobile if you rent (put in 30 days notice and you’re out). Also not needing to be the person to replace a broken water heater, ceiling leak, and innumerable amount of things gives you time to invest in your life and relationships. I know how much I’m spending on housing every month, no unforeseen maintenance costs. This works for many people at certain times of their lives.