With the normal family deductions take home would be $20K in New Jersey. Chinese nanny is $1600/m. Mortgage on $600K house is $3000/m. No insurance fees for a derm. They are in high demand and insurance is covered by the practice. There is also property tax, which is very high in NJ. Probably like $20K a year somewhere nice like Princeton. I was too generous with the savings rate but it's still over $10K a month, not $4k. Plus, there's still your husband's salary.

Anyway, that wasn't really my point. My point was that the $400K band is also a lot of upper middle class jobs like medicine, where people shop at Costco and drive Toyotas.