There's an implicit "for the best price each room could possibly bring" attached to that goal. The reasoning is basically that the cost of a hotel room (construction, upkeep, etc) is not affected too much by whether it is occupied or not. (In that way it's very similar to a seat on an airliner.) So considering your costs as a hotel operator are nearly fixed, you're quite obviously better off selling 50 rooms at $200 and then 50 more rooms at $100, than if you had kept the price at $200 and only been able to sell the first 50 rooms. Of course in the real world the pricing strategies are a lot more complicated than that and depend on having good models for how many people are willing to pay what price, and when.