It does make a very considerable difference, if you're serious about your biking, though. Plus, more expensive bikes are not necessarily lighter - there are many variables involved on the price (wrist comfort, seating type, suspensions, frame stiffness/weight, numbers and quality of gears, etc) - many more than the usual 'audiophile' choosing range.

But yeah, a lot of people buy expensive rides for the looks and have no idea what do do with them...