Correlation of Economy with Life Span?

Like any other commodity, the commodity of labor is negotiated by the "invisible hand" of capitalism. Since it is understood that it is the availability of a particular good that determines its worth, it follows that the availability of workers determines their value. So, if there were an abundance of workers of a particular skill, the wage for that skill would drop. My question is this: It seems to me that the reverse is also true, and that the economy has adjusted itself in so far that it would take the average worker a full 40 year career to reach the state know as the "American Dream" (House, Car, 2.5 kids, etc). Is this just a coincidence or has the market (i.e. the cost of same listed above) adjusted itself in accord with a typical worker's total expected labor output over a life time?