As someone who lives in the Midwest: no. You are just plain wrong.
While most cattle has some corn feed, cattle are grazing animals,meaning they literally eat constantly. Corn helps provide nutrients the cattle need to grow, but most farmers tend to feed them mostly hay or just simply let them graze on grass.
Grazing land is usually made up of land that isn't good for agriculture, either because it has low nutrient content needed for foods like corn wheat or soy, or is simply too rough, hilly, or prone to flooding to support crops.
Chickens are usually fed corn or other seeds, but font eat nearly the extent that cattle do, and produce more efficient (see calorie dense) food than crops grown on a similar size area, and can be cycled through about twice the rate it would take crops to grow, further increasing the efficiency of that land area.
Hogs are a similar story to chickens, since they cycle through fast and will eat literally anything organic you put in front of them, while goats and sheep are for all intents and purposes identical to cattle.
Even if the whole system was horribly inefficient, crops are much easier to care for and deal with. You don't have to tend them every day, you don't need to time birthing cycled to be most efficient, you don't need to move them from field to field, you don't need to have extra locations to store them over winter (since grains are usually just sold to an elevator at the end of the season) they're easier to ship and transport, and they have good profit margins. But letting non crop land go to waste would be an even bigger loss, since you have to pay the taxes on the land somehow.
So no, farmers don't waste their time and money on inefficient ways to make profit, and to say otherwise is simple deception.