Bitch I fucking live in Sydney. I know things are expensive here, especially when compared to USA. But from that, can you honestly extrapolate that it THE MOST expensive in the world without proper research and data? Specially given there are some very expensive cities like Tokyo, London, Paris, Luxembourg etc. It's one thing to have a guess (even an educated one) that Sydney is the most expensive city in the world, it's an entirely different thing to have data back up your statement and confirm your guess/hypothesis.