$72K is about $50K post tax (including one month of paid vacation). $72K is also a lower bound: I often see positions for ~95K-100K. And if you work as a contractor, ~$160K.
The national median wage is ~$35K ($27K post tax) afaik, and people live good lives on that, albeit in smaller towns.
And if you have a mortgage, you can deduct 30% of interest payments.