I would argue that it is both. If you can have the same lifestyle for $6k/m in San-Francisco than you can for $2k/m in an unnamed city in Ohio, then one would argue that you still are better off in San-Francisco, because the quality of goods you are getting is higher.
But then, it depends on the person. I wouldn't want to live in a large noisy million city; I prefer smaller, more peaceful places, and they also happen to be much cheaper to live in.