The flaw in the reasoning is an increase in the price of a ticket will not cause a decrease in demand, but rather a decrease in quantity demanded.
There is a change in quantity demanded when the price of a good changes. For example, if the price of plane tickets increase, there would be a decrease in quantity demanded for airplane travel.
There is a change in demand when other factors except for the price of a good change. For example, if there is a news that airplane travel increase lifespan, there would be an increase in demand for airplane travel.
For more information about the change in demand, please check: https://brainly.com/question/25871620