Let's say you earn a PhD in engineering and you start a company that needs plenty of other highly trained engineers. You're gonna be paying big salaries. But you'll also find that many of your highly paid people want to live where there are plenty of amenities.
They may want to be near movie theaters concert halls, professional sports stadiums, a big mix of interesting restaurants, etc. You're gonna find that highly paid knowledge workers congregate in areas with lots of amenities. And they can afford to pay more for the amenities, so the restaurants etc in the area can charge more and pay more.
This process has been happening for a LONG time already. Cities with high costs of living have been attracting knowledge workers, and the businesses nearby have been adapting to feed their expensive tastes. And those businesses can and do pay their employees more. And then people like your friend drive a long way to get one of those better paying jobs. And if they do well, they might move much closer to the high paying area.
