Theres two reason why a bike would be expensive – one is the law or diminishing returns – the more value you add to a bike, the fewer people will buy one, because not everyone will pay a bit more for something thats a bit better. Adding that value might be adding material things technology, complexity or nice metal or it might be something that gives a warm feeling in your tunny like prettiness, or cleverness or some misplaced satisfaction if having tubes welded together by white people instead of yellow people. By making and selling less your overheads per bike are higher, which means you have to charge more, which means even fewer people will buy one, which means…… Thats why the difference between a £500 bike and a £5000 bike isn’t as great as between a £50 bike and a £500 one.
The other might be to control the quantities you sell. If Orange (for instance) priced their bikes to match Specialised they’d sell as many bikes as specialised. They might not want to make and sell that many bikes, deal with that much work, make the investments that that requires, be that kind of business and live that kind of life. They might just want to sell enough bikes to be happy, have happy customers and nothing more.
There might be a third reason – that cycle buyers and weak willed weirdos who’ll buy any old crap at any old price and the manufacturers are all laughing at them and rubbing their hands with glee as they shake us til all the housekeeping falls out our pockets. But in reality buyers set and limit the prices things can be sold for to a much greater extent than they realise, especially as not one of use needs to buy a bike, let alone one that only gets ridden in circles that start and end in carparks.