but the cost of building a hotel is too extreme. first you need to be buying land if you have not any yet. it is up to you how big you want the land to be but expect this will be quite costly especially if you will be building a hotel somewhere tourists are known to go to. the building or construction will be costly in terms of money and time. you would have to ensure quality and safety having to hire engineers and architects and interior designers as well. the furniture and the equipment needed to start operations should be of high quality with reliability. not to mention your staff that you would have to pay.
Ever heard of a Condotel? Because if you do, you might not need to spend millions or billions to own a hotel from the scratch. In fact, this is one of the few alternatives if you can't afford to build or own the whole building.
And I think it is way profitable than airbnb, depends on the location, but most hotels are situated in either the a city where it is a center of businesses or in a vacation place.
Though, it's still a bit expensive compared to some typical airbnbs when you're just starting out, but it is a good start if you're aiming to have a very profitable and sustainable business in this industry.