All drinks are marked up a significant portion--it's where most profits come from in the restaurant world. You can buy coffee for a lot less. It probably won't be as fancy, but it'll probably be of similar quality for less.

People also generally perceive something that costs more as tasting better (this has been shown in several blind wine tastings). It's also something of a status symbol (although the people getting it probably won't admit it). Look at me I can pay a lot for a fancy looking cup of coffee. This is the same reason will buy a purse for thousands of dollars when one of essentially the same quality could be made and sold for under $100.