Well that analogy is slightly flawed...as you see the Kancil could probably last as long as the big car depend on how the owner maintains the car. Graphic cards last as long as it can handle the technological curve in games. Newer games are more demanding and the graphic card will eventually not be able to play any game. Unlike the junk Kancil which could still get you around.

But i agree some people are just kiasu and want the best for some odd reason and nothing to do with gaming...seriously why get a new card when you just get a 8800GT in the next few months?

Yes in the beginning the new high end may not blow the old ones away...but later as games take advantage of the newer architecture and technology...they always do...but again it takes time in this industry 6 months at least before you see anything that will take advantage of it(other than Crysis f course).