I can only on road bikes as that’s what I ride. But it seems like the biggest factor that drives up prices is a combination of weight and aerodynamics.

For just regular people, If you know where to look you can get a high end bike that was unfinished at the factory and didn’t get painted/stickered/branded and pay a fraction of the price. A lot of time the branding is what really drives up prices.

But in the very high end it’s really all about weight and aero. Professional racers will pay a hefty premium to knock a few grams off of their bikes total weight, or to get parts that are more aerodynamic and thus give you better power transfer between your bike and the road.

And then the lighter you want to get, you start getting diminished returns, and exponentially higher prices. Like if you compare a 3 pound saddle to a 1 pound saddle it might be a little bit more expensive. But then if you have a 150 gram saddle and want to get a 100 gram saddle that might be 20x the price.

Lighter parts also have to sustain the same amount of forces (and sometimes much much more) as their heavy duty steel counterparts so finding things that can undergo this amount of stress and not break plays into it as well.

And this doesn’t even go into materials. The big new thing is titanium bikes which are ridiculously expensive but will last several lifetimes if taken care of. And then carbon fiber is difficult to make and even more difficult to make well. Much lighter and than other materials but really only flexes in one direction and can be really fragile if under the wrong type of stress.