A large part of tourism is being able to brag about where you went. The cost is just a side effect. You can see this more clearly in the hierarchy of non-urban tourist destinations.

Cities like NYC and Paris have high baseline cost of doing business there. If the stuff that did cater to tourists didn't also have broad mass market appeal or other usefulness at those high price points (e.g. a hotel can serve business travelers as well) it would be priced out replaced with other stuff