Flying isn't cheap, but why is that? the first thing that comes to mind is the fuel. A passenger jet will fly 0.67 miles per galloon, that works out at 1.5 gallons for every mile travelled but because there are so many people onboard the flight that cost gets split equally into a far smaller amount. So what is it that makes flying expensive?
It's not the fuel, but everything else, from a pilot's salary to the cost of a crew, airport fees, taxes, plane maintenance and the cost of running the business in general it all gets very expensive very quickly. This awesome video by Wendover Productions breaks down the costs of flying that you may not have considered before.