In reality, the further you get towards the top, the harder it gets to stay there:
The composition of the very top income groups changed dramatically over time. Less than half (39 percent or 42 percent depending on the measure) of those in the top 1 percent in 1996 were still in the top 1 percent in 2005. Less than one-fourth of the individuals in the top 1/100th percent in 1996 remained in that group in 2005. [1]
Here's another study with similar results across all income brackets. [2] None of the brackets are very stable; people move around quite a bit.
Or, we could just sit around reading collections of personal anecdotes. Seriously, why is this article on the front page?
[1] http://www.entrepreneur.com/tradejournals/article/206340741....
[2] http://books.google.com/books?id=lhiIyq8ylUMC&lpg=PA146&...