Actually I would argue that over twice as much is not enough. Having made a similar comparison living in Phoenix the cost of 'extras' in the New York metro area is much higher. If I wanted to invest, send my daughter to a private school or go out to eat is dramatically higher.

And, what the heck do you think happens to the extra money? It goes away? The difference between 100k and the cost of living in Louisville is hopefully invested back in his own family. Even if it is wasted he is still using it.