Airports are usually pretty profitable. In other countries they are privatly owned and in demand to own and operate. In this country we don't allow that but they still make a lot of money for themselves to plow back into their operation. Also, they are financed by issuing bonds that are purchased by financial companies that manage pensions and 401K's.

I doubt that anyone here can point to any tax money you paid that went to build an airport, other than a user fee on a ticket. Besides if we didn't have airports there wouldn't be enough car rentals to provide the tax money from them to build the sports stadiums around the country.

The ATC system is also subsidized by air travellers beyond the percentage it is used by the airlines.