3 ms·... primarily because households which would have been middle-class now have upper-class incomes instead.by cperciva 8mo ago... primarily because households which would have been middle-class now have upper-class incomes instead.aydyn 8mo agoAnd the increase in low income is due to...?cperciva 8mo agoMore people attending college, for a start. The increase in low-income households is much smaller than the increase in high-income households.