It's also hard to stay on top, and it gets harder the closer you are: the turnover of individuals in these extreme upper brackets is high [0].
The composition of the very top income groups changed dramatically over time. Less than half (39% or 42% depending on the measure) of those in the top 1% in 1996 were still in the top 1% in 2005. Less than one-fourth of the individuals in the top 1/100th percent in 1996 remained in that group in 2005.
Year-to-year income of the top 1% is probably a poor measure of "staying on top".
I would like to see those numbers controlled for wealth. Some of those people whose incomes move in and out of the top 1% are just in boom-or-bust jobs or own boom-or-bust businesses or investments. Others are big earners who recently retired to extremely comfortable fixed incomes.
Neither category really fits what I would think of as someone losing his or her "on top" status.
On the other hand, moving from a high-income high cost-of-living area (SF or NYC) to a lower-income, low cost-of-living area (Boulder, KC, or Charlotte) will technically move you out of the 1% while improving your standard of living.
The composition of the very top income groups changed dramatically over time. Less than half (39% or 42% depending on the measure) of those in the top 1% in 1996 were still in the top 1% in 2005. Less than one-fourth of the individuals in the top 1/100th percent in 1996 remained in that group in 2005.
[0] http://ntj.tax.org/wwtax/ntjrec.nsf/F95C00D9840D35F2852575F4...