I always find these numbers a bit deceptive when you try and use them in the real world. Lets compare 2 people at 1k/year.
That is a pretty big difference.
Given 1 less year in the market (call it like 8%) and those numbers are pretty close. In the real world is the difference huge (25%+) or is it pretty small (~5%). In the real world I think for most people they end up with the smaller difference most of the time as it is rare to have event that takes you out of the game (i.e. dying:)). In the end we just end up seeing a lot of the effects of volatility of the last year (the difference between being +20% for the year or -20%). Now there are definitely periods with good/bad returns. I jus think these charts tend to exxagerate things. The 1999 and 2002 person are going to be a lot closer than charts like this indicated.