Top 1% income includes a lot of people who are just barely in that 1% and get most of their money from income. Many people go in and out of that top 1% in good and bad years so it's not as fixed as your thinking. Wealthy people may even have a net negative income for multiple years while keeping a 7 figure lifestyle.
Even wealth is tricky as someone's wealth at death is probably a better indicator. Though again complicated by trusts that are not in their name.
Citations? I think the top 1% is a much more stable group than this indicates. Top 10%, I would completely agree with here.
And I fully accept I could be wrong. I'm currently googling a few things, to see if I am off here. I'm asking not to be a jerk, but this is put forward as fact here. So I'm assuming you have actual numbers to back this up.
Did you even read the paper? From 1991-2005, the odds of remaining in the top 1% for 5 years have ranged from 21% (in 1999) to 36% (in 1994). Intermediate results are more or less the same from 2005-2010.
I'm curious how much of that is falling out of the top, and how much is the to accelerating ever higher. And you still need to adjust for inherited wealth.
That is, of those that fell out, how many got there from inheritance?
1% is a rather arbitrary division point. Even if you assume that there exists a stable cluster of wealth at the top, why would it be bounded around 1%? It is much more likely that the group is either smaller than 1%, or larger.
Suppose it's larger, then the group could still be stable, but the churn between people at 1.1% and 0.9% would still cause the arbitrary measurement of top 1% to change a lot.
Now suppose the group is smaller than 1%, and the churn is instead at the top of the cluster directly beneath the stable group at the top, but still causes the composition of the top 1% to change constantly.
Even wealth is tricky as someone's wealth at death is probably a better indicator. Though again complicated by trusts that are not in their name.