The error I always see in these analyses of income percentiles, while not always explicitly stated but but usually inferred, is that the income groups remain st

The error I always see in these analyses of income percentiles, while not always explicitly stated but but usually inferred, is that the income groups remain static. But this isn't true. This analysis of churn shows households move across income quintiles over a decade. https://www.clevelandfed.org/publications/economic-commentary/2016/ec-201606-income-inequality-and-mobility https://www.clevelandfed.org/publications/economic-commentar... For the 2nd to the 5th quintile, only 3% to 23% of households are still in the same quintile a decade later. Among the lowest, it's higher at 64%, which may seem disconcerting, but one must recognize that retirees would fall in that group and often have low income for the duration of their retirement as they live off savings. And intuitively this makes sense - people leave home to start careers often make low incomes and see progressively higher income until retirement, at which point they see a large drop incomes. So while it may be true that the wealthiest American fuel spending, that group of wealthiest Americans is constantly changing.