Because they wanted to live there, basically. If you view a city as nothing more than rent and groceries and you get most of your entertainment at home, then b

Because they wanted to live there, basically. If you view a city as nothing more than rent and groceries and you get most of your entertainment at home, then big cities probably don’t feel like a good value proposition. But if you enjoy going to events, eating out, socializing with a wide variety of motivated people, and otherwise experiencing everything a city has to offer, a big city is the place to be. Neither answer is “right” for everyone. It’s an individual preference.