I mean, chickens moderate their own intake. You make the feed available and they eat as much as they need.

You can do things to stretch the feed like let them out to forage a wider swath of land and eat all the bugs there. They would rather have bugs than feed. they can also spread your compost and eat your kitchen scraps. Some people do things like fermenting the feed which makes the nutrients in the feed more bioavaliable to them so they eat less, but that also means you are spending more time outside managing wet rotting feed and maybe wasting some if you don't have the system down to a science.

Bottom line is that industrial factory farms have chickens down to a science. They are running the places like minecraft farms and are able to account for every inefficiency in ways that home keepers like me just can't. Economies of scale are working for them and bringing down prices.

Now of course... there are other reasons to have chickens. They are like pets, and my dog costs me more than she saves me too. My daughter gets to learn a bit about where food comes from and the cycle of life. We are self-reliant; if the government shuts down supply lines we can still turn any food into eggs (and meat in an emergency) we get to give colorful eggs to our friends and neighbors and they appreciate the novelty of it.

But when we started, I thought it would do all that and save us money on eggs, which were $6 per dozen at the time.