A lot of these people spend money on things like travel, going out to eat, cable, cell phones, etc.
Life really isn't that expensive unless you buy a ton of useless stuff.
Granted, I don't have a mortgage and we have two older cars, but I still spend about $2000/month for a family of four.
Costs of living vary greatly by location. $2000/mo wouldn't cover my mortgage and transportation costs, and I also have older vehicles. Anything less would require relocating to an area with higher crime and even worse schools than we're dealing with now.
Eating out is not a luxury when two wage earners are spending significantly more time outside the house earning wages, between increased working hours and commute times. It's an opportunity cost that must be absorbed. There are far more opportunity costs, relating to health, child development, etc.
