There are some brands of bicycles that can cost more than the down payment on a car. Why? Surely making a bike lightweight and reliable isn’t so difficult that it warrants that price? Is it just the brand name or maybe it has to do with customization options?
Although this YouTube video is about motorbikes and mountain bikes, much of the context is applicable to bicycles at large. And is also within the ballpark of an automobile down payment.
https://youtu.be/BS9ugdl1FZc
Borrowing some of the points from that video, a high-end bicycle – let’s say a road bike – is very close to what could actually be used in competitive road cycling, with all the technological and material sciences advances included. Whereas a standard car like a Toyota Corolla would need substantial further investment to bring it to competition grade (eg rallying). And a high-end, track-inspires road-legal car would be exceeding $100,000 easily.
Certainly, in the average quality range, the price of your average road bike and your average automobile will be a chasm away. But I figured your question is focusing on the high end of bicycles.