Two points from AA5's post I'd like to comment on.
1. Yes the FAA provides infrastructure grants to airports. While those grants cover a large portion of the cost, there is always a local match, and a limit on how much money an airport can get. The FAA provides $0 to fund the operation and maintenance of the airport. Say it with me, $0. The utility bills, staffing, mowing, plowing snow, replacing light bulbs, painting markings, etc., all local funded.
2. It is a violation of Grant Assurances for airport revenue to be diverted from the airport. The Municipal Government can't touch that money. Even if the airport makes a profit, which few actually do, that money has to stay on the airport. Most airports actually depend on receiving money from the local government to fund at least part their operations.
And BTW, most airports are government owned and operated. Meaning the Airport Manager and staff are city/county employees. Pay and benefits may not be bad, but no one in local government is getting rich. Doesn't matter how much money the airport makes, the staff is on a municipal pay scale. There is no profit sharing, no bonuses, not even a Christmas ham.