There are also good reasons why "where they can find a well-paying job" usually coincides with "where there are a lot of people."

Generally speaking, a person's salary corresponds to a pretty reasonable estimate of how much good they are doing for society. It's easier to do more good for more people when more people are around, e.g. a restaurant does more benefit to more people by being close to a lot of people, instead of being in the middle of nowhere. So generally people will get paid more if they have jobs closer to a lot of people.