I’d love to be corrected on this.
https://www.aei.org/carpe-diem/some-amazing-findings-on-inco...
This is how they counter all the talk about the 1%. They suggest that 56% of people will be in the top 10% for one year or more. In their entire working lives.
Distortions include:
-income is not wealth
-some kinds of income are very uneven year-over-year
-jumping into the top bracket for only one year doesn't indicate income or class mobility
-most of the top 1% of income do in fact stay in the top 1% of income
People who earn a lot in one year but don't become wealthy may include:
-actors who get one TV commercial
-waiters at high-end restaurants who burn out
-realtors who get a few good sales in a row
-victims of disabling accidents receiving large insurance payouts
-oil and other trade workers in Alaska
-minor lottery winners
-people cashing in a retirement fund to deal with emergency spending
The fact that America is a land of random windfalls doesn't help with social mobility. A family with multi-generational poverty gets a windfall and immediately has to spend it just trying to catch up a bit.
The other misleading thing is it looks at 44 years of longitudinal data, and doesn't make corrections for differences between the early years and later years. Income has become more polar in the last 40 years, so the current numbers are a fair bit worse than the average numbers of the last 4.4 decades.
What it really comes down to is that the upper tail of the "reliable income" distributions is thin enough that a large fraction of the people who end up in various "top N%" buckets are there due to various windfalls, lumpiness of income (e.g. a writer getting an advance that they live on for a few years while writing the book), etc, etc.
Which is, by the way, why the way we do progressive taxation is a bit weird. Progressive taxation with tax brackets based on lifetime earnings, as opposed to current-year income, would make a lot more sense in some ways...