Ok, I'll revise my statement: it doesn't make sense to live in Manhattan if you're not making at least $200k/year consistently and you're over the age of 30.
It might make sense if you're 24 and you're happy living with roommates in a $3k/month studio that has been converted into a 3-bedroom (which I have actually seen).
And if you want to have a family with 3 kids, then you'd better be pulling down $800k annually.
A lot of people in New York get by with a lot less. $800k for a family of 5 is nearly six times the median income for that family size in NYC. If that's your idea of "getting by", your perspective is wildly distorted from the average New Yorker, much less the average American.