I figure one reason they make a profit is because they sell a reasonable product at a reasonable price. When I look at fast food outlets the ones that appear to be the best known are the burger chains. Personally I refuse to eat anything from McDonalds because it's just garbage. I last tasted what they call food three years ago and all I could wonder is why people pay money for such trash, let alone stand in line to pay for it. Burger King isn't much better. A chain like Arby's at least offers a higher quality product but the price is just too high for what you get - a couple of sandwiches and drinks at the fast food joint can end up costing more than a sit down meal for two at a diner, even if a budget diner. And then Chick-Fil-A comes along, offering a product that doesn't hit you with a $25 bill for two people to have a modest meal and is something you might actually want to eat.
Political issues aside, I'd choose to eat at Chick-Fil-A. I've driven past numerous branches of other fast food chains, even when I've been hungry.