On the other hand, at the micro level people actually experience, I think the cultural dynamic is more important. It determines how people feel about the economy.
The people she talks to believed their educations and backgrounds (most of them grew up in middle-class homes) would guarantee some financial stability
Upward mobility is ideologically important to any major, modern political camp. Few deal with downward mobility in any way. Individuals will have a much tougher time politically tolerating being poorer than their parents (or their cohort) than just being poor. Losing is more emotional than winning and the grudge lasts longer than the opposite.
Ideologically, I think most of us would say that social class should not be inherited. Emotionally, few of us can live with downward moves in the economic hierarchy. It creates an unmistakable feeling of having been robbed of one's birthright.