Sure, the department store bikes are garbage, but
you can get a perfectly good brand name basic city bike for well under $1000.
Bikes mass is marginal compared to your body weight especially if you're average weight. A basic bike is 34 lbs and you are 175 lbs. And the weight only makes a big difference when climbing hills.
You're much better off losing a few pounds of fat than spending a few grand to get 10 lbs off the bike and shaving 2% off the required muscle power per mile :)
In general, about weight, I agree. One exception is rotating mass (i.e., wheels). A light, well-built wheel handles a lot better than a heavy one. No amount of personal weight loss is going to make up for that.
Beyond mass, the behavior of shifters and brakes on nice bikes is much, much crisper and more predictable than on cheaper models. They also have better capacity for tuning (e.g., to eliminate chain rub, or accommodate a high-range sprocket set), and are more likely to stay in proper adjustment for longer. This makes riding a lot more fun -- the machine is very responsive to your wishes, and you forget it's there.
You probably are aware of this, but I felt a need to mention some of the advantages of a nice bike.
You're right about the difference that lowering your body mass makes. It's the easiest way to drop the weight that you have to pedal around. I have a cyclist friend who loves to claim "I just took a $1000 shit," the joke being that that's how much it would cost him to get a $poop_mass lighter bicycle.
However, this doesn't apply to racers. If it's going to speed someone up by 2%, and he's got the money, and he wants that last tiny advantage, he may just drop the cash on a $1500 wheel set.
Heck, if it's going to speed him up enough to make a 50m difference over a 200km road race, it's worth the price to an actual racer. (And there will probably considerable time spent tweaking even the best of things to perfection before each race.) But they are so very, very few in number, even if it's sometimes hard to tell when you pass that one local cafe that is populated exclusively by spandex-wearing, logo-encrusted latte drinkers who gather to talk about their bikes.
Bikes mass is marginal compared to your body weight especially if you're average weight. A basic bike is 34 lbs and you are 175 lbs. And the weight only makes a big difference when climbing hills.
You're much better off losing a few pounds of fat than spending a few grand to get 10 lbs off the bike and shaving 2% off the required muscle power per mile :)