Most companies are willing to negotiate, especially when you have a counter-offer. So in general, it is good advice. Most companies do not have the attitude of "I don't care how much money you would make at an other company, because you want to join our company" because they know that most people value some combination of enjoying their work, and how much they get paid, not just one or the other.

>The first part is very personal. People having mortgage and two kids just overvalue themselves. Immigrants in US (and I guess everywhere) just don't need as much money as they don't see the neighbour's grass. Can you explain what you are saying here? Are you saying that only immigrants are willing to take the offers you make, or that you make higher offers to people who overvalue themselves?