If I were so inclined, I would have a look at what else ARFF does on an airport other than waiting for an aircraft to crash. Most international airports are small cities in their own right and much like an inner-city department, the airport fire department would respond to calls in the terminal not directly related to aircraft operations.
While true that they may never respond to an aircraft accident, they certainly save lives in the terminal and support buildings that would otherwise be lost to things like heart attacks, choking on that last French fry, or responding to a fire in the baggage area caused by the idiot who decided fireworks were a good idea to check.
Not exactly a waste of money in my mind.