It's not about money, for me at least, but the experience. Hotels are generally boring, soulless, and isolated, whereas AirBnBs tend to be more like an actual home: comfortable, with personality, located in the place you are there to visit. You generally get access to a kitchen. A hotel is more convenient if you're just crashing somewhere for a night or two, but if you are trying to visit a place, and enjoy the time you spend living there, an AirBnB is better.