A lot of great answers...
Why by a Bentley when a Honda will get you where you need to go, (often with better mpg?) (Love that one).
Why buy a $100 knife instead of a $50, or a $30 over a $10 one, (another good one).
To add to that, why buy a $1000 Movado when a $20 Timex will tell you the same time of day?
In the wise words of my 3 year old son, why?
Simply, "becuz".
For some it's the status symbol, for others it's the trend just to be cool, for others it's the appreciation of the art, yet still for others it's a true appreciation of the craftsmanship. Different strokes for different folks...
Buy what you like, buy what you want, buy what you can afford, (and if you really like something you want but can't afford it, save up until you can). But it should not matter why anybody else buys what they like, want, and can afford... And so long as the bills are getting paid, and responsibilities arent being neglected, nobody should feel guilty about what they bought with their money, be it a $15 Schrade, or a $1000 shirogorov.